Introduce optional, string_view, and span

sqlpp::optional is an alias for std::optional for C++17 and beyond.
Otherwise, it is a simple and incomplete backport.
For older versions of C++, the library offers simple back

Similar for string_view and span.

include/sqlpp11/compat/optional.h

@@ -0,0 +1,247 @@
+#pragma once
+
+/*
+ * Copyright (c) 2024, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice, this
+ *   list of conditions and the following disclaimer in the documentation and/or
+ *   other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef _MSVC_LANG
+#define CXX_STD_VER _MSVC_LANG
+#else
+#define CXX_STD_VER __cplusplus
+#endif
+
+#if CXX_STD_VER >= 201703L
+#include <optional>
+namespace sqlpp
+{
+  template <class T>
+  using optional = std::optional<T>;
+
+  using std::nullopt_t;
+  using std::nullopt;
+
+  using std::bad_optional_access;
+}  // namespace sqlpp
+
+#else // incomplete backport of std::optional
+
+#include <utility>
+#include <stdexcept>
+
+namespace sqlpp
+{
+  class nullopt_t
+  {
+  };
+  constexpr nullopt_t nullopt;
+
+  class bad_optional_access : public std::exception
+  {
+    public:
+      ~bad_optional_access() override = default;
+      const char* what() const noexcept override
+      {
+        return "bad optional access";
+      }
+  };
+
+  template <class T>
+  class optional
+  {
+    // Unnamed union, injecting members into scope.
+    union
+    {
+      char _nothing;
+      T _value;
+    };
+    bool _active = false;
+
+    // Placement new
+    template<typename... Args>
+    void create(Args&&... args)
+    {
+      new ((void*)std::addressof(_value)) T(std::forward<Args>(args)...);
+      _active = true;
+    }
+
+    void destroy()
+    {
+      if (_active)
+      {
+       _value.~T();
+      }
+    }
+
+  public:
+    optional() noexcept : _nothing(), _active(false)
+    {
+    }
+    optional(T t) : _active(true)
+    {
+      create(std::move(t));
+    }
+
+    optional(const optional&) = default;
+    optional(optional&&) = default;
+    optional(const nullopt_t&) noexcept
+    {
+    }
+
+    optional& operator=(const optional&) = default;
+    optional& operator=(optional&&) = default;
+    optional& operator=(const nullopt_t&) noexcept
+    {
+      destroy();
+    }
+
+    ~optional() {
+      destroy();
+    }
+
+    bool has_value() const
+    {
+      return _active;
+    }
+
+    explicit operator bool() const
+    {
+      return _active;
+    }
+
+    T& operator*()
+    {
+      return _value;
+    }
+
+    const T& operator*() const
+    {
+      return _value;
+    }
+
+    const T& operator->() const
+    {
+      return _value;
+    }
+
+    template<typename... Args>
+    optional& emplace(Args&&... args) {
+      create(std::forward<Args>(args)...);
+    }
+
+    T& value()
+    {
+      if (_active)
+        return _value;
+      throw bad_optional_access();
+    }
+
+    template<typename U>
+    T value_or(U&& u)
+    {
+      if (_active)
+        return _value;
+      return std::forward<U>(u);
+    }
+
+    const T& value() const
+    {
+      if (_active)
+        return _value;
+      throw bad_optional_access();
+    }
+
+    void reset()
+    {
+      destroy();
+    }
+  };
+
+  template <class L, class R>
+  bool operator==(const optional<L>& left, const optional<R>& right)
+  {
+    if (static_cast<bool>(left) != static_cast<bool>(right))
+      return false;
+    if (!static_cast<bool>(left))
+      return true;
+    return *left == *right;
+  }
+
+  template <class L, class R>
+  bool operator==(const optional<L>& left, const R& right)
+  {
+    if (!static_cast<bool>(left))
+      return false;
+    return *left == right;
+  }
+
+  template <class L, class R>
+  bool operator==(const L& left, const optional<R>& right)
+  {
+    if (!static_cast<bool>(right))
+      return false;
+    return left == *right;
+  }
+
+  template <class L, class R>
+  bool operator!=(const optional<L>& left, const optional<R>& right)
+  {
+    if (static_cast<bool>(left) != static_cast<bool>(right))
+      return true;
+    if (!static_cast<bool>(left))
+      return false;
+    return *left != *right;
+  }
+
+  template <class L, class R>
+  bool operator!=(const optional<L>& left, const R& right)
+  {
+    if (!static_cast<bool>(left))
+      return true;
+    return *left != right;
+  }
+
+  template <class L, class R>
+  bool operator!=(const L& left, const optional<R>& right)
+  {
+    if (!static_cast<bool>(right))
+      return true;
+    return left != *right;
+  }
+
+  template<class T>
+  bool operator==(const optional<T>& left, const nullopt_t&)
+  {
+    return !left;
+  }
+
+  template<class T>
+  bool operator==(const nullopt_t& n, const optional<T>& right)
+  {
+    return !right;
+  }
+
+}  // namespace sqlpp
+
+#endif

include/sqlpp11/compat/span.h

@@ -1,7 +1,7 @@
 #pragma once
 
 /*
- * Copyright (c) 2013-2015, Roland Bock
+ * Copyright (c) 2024, Roland Bock
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification,
@@ -26,28 +26,52 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/integral/data_type.h>
-#include <sqlpp11/field_spec.h>
+#ifdef _MSVC_LANG
+#define CXX_STD_VER _MSVC_LANG
+#else
+#define CXX_STD_VER __cplusplus
+#endif
+
+#if CXX_STD_VER >= 202002L
+#include <span>
+namespace sqlpp
+{
+  template<typename T>
+  using span = std::span<T>;
+}  // namespace sqlpp
+
+#else // incomplete backport of std::span
 
 namespace sqlpp
 {
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, integral, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, integral, CanBeNull>>
+  template <typename T>
+  class span
   {
-    template <typename Target>
-    void _bind(Target& target, size_t index)
+    const T* _data = nullptr;
+    size_t _size = 0u;
+  public:
+    constexpr span() = default;
+    constexpr span(const T* data, size_t size) : _data(data), _size(size)
     {
-      target._bind_integral_result(index, &this->_value, &this->_is_null);
     }
 
-    template <typename Target>
-    void _post_bind(Target& target, size_t index)
+    const char* data() const
     {
-      target._post_bind_integral_result(index, &this->_value, &this->_is_null);
+      return _data;
     }
+
+    size_t size() const
+    {
+      return _size;
+    }
+
+    const T& operator[](size_t i) const
+    {
+      return *(_data + i);
+    }
+
   };
+
 }  // namespace sqlpp
+
+#endif

include/sqlpp11/compat/string_view.h

@@ -0,0 +1,106 @@
+#pragma once
+
+/*
+ * Copyright (c) 2024, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice, this
+ *   list of conditions and the following disclaimer in the documentation and/or
+ *   other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef _MSVC_LANG
+#define CXX_STD_VER _MSVC_LANG
+#else
+#define CXX_STD_VER __cplusplus
+#endif
+
+#if CXX_STD_VER >= 201703L
+#include <string_view>
+namespace sqlpp
+{
+  using string_view = std::string_view;
+}  // namespace sqlpp
+
+#else // incomplete backport of std::string_view
+
+#include <utility>
+#include <string>
+#include <iosfwd>
+
+namespace sqlpp
+{
+  class string_view
+  {
+    const char* _data = nullptr;
+    size_t _size = 0u;
+  public:
+    constexpr string_view() = default;
+    string_view(const std::string& source) : _data(source.data()), _size(source.size())
+    {
+    }
+
+    constexpr string_view(const char* data, size_t size) : _data(data), _size(size)
+    {
+    }
+
+    string_view(const char* data) : _data(data), _size(std::char_traits<char>::length(data))
+    {
+    }
+
+    const char* data() const
+    {
+      return _data;
+    }
+
+    size_t size() const
+    {
+      return _size;
+    }
+
+    operator std::string() const
+    {
+      return std::string(_data, _size);
+    }
+  };
+
+  inline bool operator==(const string_view& left, const string_view& right)
+  {
+    if (left.size() != right.size())
+      return false;
+    return std::char_traits<char>::compare(left.data(), right.data(), left.size()) == 0;
+  }
+
+  inline bool operator!=(const string_view& left, const string_view& right)
+  {
+    if (left.size() != right.size())
+      return true;
+    return std::char_traits<char>::compare(left.data(), right.data(), left.size()) != 0;
+  }
+
+  inline std::ostream& operator<<(std::ostream& os, const string_view& sv)
+  {
+    return os << std::string(sv);
+  }
+
+
+}  // namespace sqlpp
+
+#endif

include/sqlpp11/data_types/blob.h

@@ -32,7 +32,6 @@
 #include <sqlpp11/data_types/blob/expression_operators.h>
 #include <sqlpp11/data_types/blob/column_operators.h>
 #include <sqlpp11/data_types/blob/parameter_value.h>
-#include <sqlpp11/data_types/blob/result_field.h>
 
 // blob specific functions
 #include <sqlpp11/data_types/text/like.h>

include/sqlpp11/data_types/blob/data_type.h

@@ -30,6 +30,7 @@
 #include <cstdint>
 
 #include <sqlpp11/type_traits.h>
+#include <sqlpp11/compat/span.h>
 #include <sqlpp11/logic.h>
 
 namespace sqlpp
@@ -38,6 +39,7 @@ namespace sqlpp
   {
     using _traits = make_traits<blob, tag::is_value_type>;
     using _cpp_value_type = std::vector<std::uint8_t>;
+    using _result_type = sqlpp::span<std::uint8_t>;
 
     template <typename T>
     using _is_valid_operand = ::sqlpp::logic::any_t<is_blob_t<T>::value, is_text_t<T>::value>;

include/sqlpp11/data_types/blob/result_field.h

@@ -1,84 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2017, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/blob/data_type.h>
-#include <sqlpp11/field_spec.h>
-#include <ostream>
-#include <string>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, blob, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, blob, CanBeNull>>
-  {
-    const uint8_t* blob{nullptr};  // Non-owning
-    size_t len{};
-
-    template <typename Target>
-    void _bind(Target& target, size_t index)
-    {
-      target._bind_blob_result(index, &blob, &len);
-      if (blob)
-        this->_value.assign(blob, blob + len);
-      else
-        this->_value.clear();
-      this->_is_null = (blob == nullptr);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t index)
-    {
-      target._post_bind_blob_result(index, &blob, &len);
-      if (blob)
-        this->_value.assign(blob, blob + len);
-      else
-        this->_value.clear();
-      this->_is_null = (blob == nullptr);
-    }
-  };
-
-  template <typename Db, typename NameType, bool CanBeNull>
-  inline std::ostream& operator<<(
-      std::ostream& os, const result_field_t<Db, field_spec_t<NameType, blob, CanBeNull>>& e)
-  {
-    if (e.is_null())
-    {
-      return os << "NULL";
-    }
-    else
-    {
-      std::vector<uint8_t> value = e.value();
-      std::string value_str(value.begin(), value.end());
-      return os << value_str;
-    }
-  }
-}  // namespace sqlpp

include/sqlpp11/data_types/boolean.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/boolean/expression_operators.h>
 #include <sqlpp11/data_types/boolean/column_operators.h>
 #include <sqlpp11/data_types/boolean/parameter_value.h>
-#include <sqlpp11/data_types/boolean/result_field.h>

include/sqlpp11/data_types/boolean/data_type.h

@@ -34,6 +34,7 @@ namespace sqlpp
   {
     using _traits = make_traits<boolean, tag::is_value_type>;
     using _cpp_value_type = bool;
+    using _result_type = bool;
 
     template <typename T>
     using _is_valid_operand = is_boolean_t<T>;

include/sqlpp11/data_types/boolean/result_field.h

@@ -1,53 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/boolean/data_type.h>
-#include <sqlpp11/field_spec.h>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, boolean, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, boolean, CanBeNull>, signed char>
-  {
-    template <typename Target>
-    void _bind(Target& target, size_t index)
-    {
-      target._bind_boolean_result(index, &this->_value, &this->_is_null);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t index)
-    {
-      target._post_bind_boolean_result(index, &this->_value, &this->_is_null);
-    }
-  };
-}  // namespace sqlpp

include/sqlpp11/data_types/day_point.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/day_point/expression_operators.h>
 #include <sqlpp11/data_types/day_point/column_operators.h>
 #include <sqlpp11/data_types/day_point/parameter_value.h>
-#include <sqlpp11/data_types/day_point/result_field.h>

include/sqlpp11/data_types/day_point/data_type.h

@@ -35,6 +35,7 @@ namespace sqlpp
   {
     using _traits = make_traits<day_point, tag::is_value_type>;
     using _cpp_value_type = ::sqlpp::chrono::day_point;
+    using _result_type = ::sqlpp::chrono::day_point;
 
     template <typename T>
     using _is_valid_operand = is_day_or_time_point_t<T>;

include/sqlpp11/data_types/day_point/result_field.h

@@ -1,70 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2015-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/day_point/data_type.h>
-#include <sqlpp11/field_spec.h>
-#include <ostream>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, day_point, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, day_point, CanBeNull>>
-  {
-    template <typename Target>
-    void _bind(Target& target, size_t index)
-    {
-      target._bind_date_result(index, &this->_value, &this->_is_null);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t index)
-    {
-      target._post_bind_date_result(index, &this->_value, &this->_is_null);
-    }
-  };
-
-  template <typename Db, typename NameType, bool CanBeNull>
-  inline std::ostream& operator<<(
-      std::ostream& os, const result_field_t<Db, field_spec_t<NameType, day_point, CanBeNull>>& e)
-  {
-    if (e.is_null())
-    {
-      os << "NULL";
-    }
-    else
-    {
-      const auto ymd = ::date::year_month_day{e.value()};
-      os << ymd;
-    }
-    return os;
-  }
-}  // namespace sqlpp

include/sqlpp11/data_types/floating_point.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/floating_point/expression_operators.h>
 #include <sqlpp11/data_types/floating_point/column_operators.h>
 #include <sqlpp11/data_types/floating_point/parameter_value.h>
-#include <sqlpp11/data_types/floating_point/result_field.h>

include/sqlpp11/data_types/floating_point/data_type.h

@@ -34,6 +34,7 @@ namespace sqlpp
   {
     using _traits = make_traits<floating_point, tag::is_value_type>;
     using _cpp_value_type = double;
+    using _result_type = double;
 
     template <typename T>
     using _is_valid_operand = is_numeric_t<T>;

include/sqlpp11/data_types/floating_point/result_field.h

@@ -1,54 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/exception.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/type_traits.h>
-#include <sqlpp11/data_types/floating_point/data_type.h>
-#include <sqlpp11/field_spec.h>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, floating_point, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, floating_point, CanBeNull>>
-  {
-    template <typename Target>
-    void _bind(Target& target, size_t index)
-    {
-      target._bind_floating_point_result(index, &this->_value, &this->_is_null);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t index)
-    {
-      target._post_bind_floating_point_result(index, &this->_value, &this->_is_null);
-    }
-  };
-}  // namespace sqlpp

include/sqlpp11/data_types/integral.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/integral/expression_operators.h>
 #include <sqlpp11/data_types/integral/column_operators.h>
 #include <sqlpp11/data_types/integral/parameter_value.h>
-#include <sqlpp11/data_types/integral/result_field.h>

include/sqlpp11/data_types/integral/data_type.h

@@ -34,6 +34,7 @@ namespace sqlpp
   {
     using _traits = make_traits<integral, tag::is_value_type>;
     using _cpp_value_type = int64_t;
+    using _result_type = int64_t;
 
     template <typename T>
     using _is_valid_operand = is_numeric_t<T>;

include/sqlpp11/data_types/no_value.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/no_value/expression_operators.h>
 #include <sqlpp11/data_types/no_value/column_operators.h>
 #include <sqlpp11/data_types/no_value/parameter_value.h>
-#include <sqlpp11/data_types/no_value/result_field.h>

include/sqlpp11/data_types/no_value/result_field.h

@@ -1,70 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/data_types/no_value/data_type.h>
-#include <sqlpp11/field_spec.h>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, no_value_t, CanBeNull>>
-  {
-    template <typename Target>
-    void _bind(Target& /*unused*/, size_t /*unused*/)
-    {
-    }
-
-    template <typename Target>
-    void _post_bind(Target& /*unused*/, size_t /*unused*/)
-    {
-    }
-
-    void _validate() const
-    {
-    }
-
-    void _invalidate() const
-    {
-    }
-
-    constexpr bool is_null() const
-    {
-      return true;
-    }
-  };
-
-  template <typename Db, typename NameType, bool CanBeNull>
-  inline std::ostream& operator<<(
-      std::ostream& os,
-      const result_field_t<Db, field_spec_t<NameType, no_value_t, CanBeNull>>& /*unused*/)
-  {
-    os << "NULL";
-    return os;
-  }
-}  // namespace sqlpp

include/sqlpp11/data_types/text.h

@@ -32,7 +32,6 @@
 #include <sqlpp11/data_types/text/expression_operators.h>
 #include <sqlpp11/data_types/text/column_operators.h>
 #include <sqlpp11/data_types/text/parameter_value.h>
-#include <sqlpp11/data_types/text/result_field.h>
 
 // text specific functions
 #include <sqlpp11/data_types/text/like.h>

include/sqlpp11/data_types/text/data_type.h

@@ -28,12 +28,17 @@
 
 #include <sqlpp11/type_traits.h>
 
+#include <string>
+
+#include <sqlpp11/compat/string_view.h>
+
 namespace sqlpp
 {
   struct text
   {
     using _traits = make_traits<text, tag::is_value_type>;
     using _cpp_value_type = std::string;
+    using _result_type = sqlpp::string_view;
 
     template <typename T>
     using _is_valid_operand = is_text_t<T>;

include/sqlpp11/data_types/text/operand.h

@@ -28,9 +28,7 @@
 
 #include <string>
 #include <utility>
-#if __cplusplus >= 201703L
-#include <string_view>
-#endif
+#include <sqlpp11/compat/string_view.h>
 #include <sqlpp11/type_traits.h>
 #include <sqlpp11/alias_operators.h>
 
@@ -51,16 +49,14 @@ namespace sqlpp
     text_operand(_value_t t) : _t(std::move(t))
     {
     }
-#if __cplusplus >= 201703L
-    // allow construction from an std::string_view
-    text_operand(std::string_view t) : _t(t)
+    // allow construction from an sqlpp::string_view
+    text_operand(sqlpp::string_view t) : _t(t)
     {
     }
     // additional const char* overload, required to disambiguate
     text_operand(const char* t) : _t(t)
     {
     }
-#endif
 
     text_operand(const text_operand&) = default;
     text_operand(text_operand&&) = default;

include/sqlpp11/data_types/text/parameter_value.h

@@ -32,9 +32,7 @@
 #include <sqlpp11/data_types/text/wrap_operand.h>
 #include <sqlpp11/data_types/text/operand.h>
 
-#if __cplusplus >= 201703L
-#include <string_view>
-#endif
+#include <sqlpp11/compat/string_view.h>
 
 namespace sqlpp
 {
@@ -51,8 +49,7 @@ namespace sqlpp
       target._bind_text_parameter(index, &_value, _is_null);
     }
 
-#if __cplusplus >= 201703L
-    parameter_value_base& operator=(const std::string_view& val)
+    parameter_value_base& operator=(const sqlpp::string_view& val)
     {
       _value = val;
       _is_null = false;
@@ -65,6 +62,5 @@ namespace sqlpp
       _is_null = false;
       return *this;
     }
-#endif
   };
 }  // namespace sqlpp

include/sqlpp11/data_types/text/result_field.h

@@ -1,87 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/text/data_type.h>
-#include <sqlpp11/field_spec.h>
-#include <ostream>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, text, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, text, CanBeNull>>
-  {
-    const char* text{nullptr};  // Non-owning
-    size_t len{};
-
-    template <typename Target>
-    void _bind(Target& target, size_t index)
-    {
-      target._bind_text_result(index, &text, &len);
-      if (text)
-      {
-        this->_value.assign(text, len);
-      }
-      else
-      {
-        this->_value.assign("");
-      }
-      this->_is_null = (text == nullptr);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t index)
-    {
-      target._post_bind_text_result(index, &text, &len);
-      if (text)
-      {
-        this->_value.assign(text, len);
-      }
-      else
-      {
-        this->_value.assign("");
-      }
-      this->_is_null = (text == nullptr);
-    }
-  };
-
-  template <typename Db, typename NameType, bool CanBeNull>
-  inline std::ostream& operator<<(
-      std::ostream& os, const result_field_t<Db, field_spec_t<NameType, text, CanBeNull>>& e)
-  {
-    if (e.is_null())
-    {
-      return os << "NULL";
-    }
-
-    return os << e.value();
-  }
-}  // namespace sqlpp

include/sqlpp11/data_types/text/wrap_operand.h

@@ -27,21 +27,14 @@
  */
 
 #include <utility>
-#if __cplusplus >= 201703L
-#include <string_view>
-#endif
+#include <sqlpp11/compat/string_view.h>
 #include <sqlpp11/type_traits.h>
 #include <sqlpp11/wrap_operand.h>
 
 namespace sqlpp
 {
   struct text_operand;
-
-#if __cplusplus >= 201703L
-  using checked_type = std::string_view;
-#else
-  using checked_type = std::string;
-#endif
+  using checked_type = sqlpp::string_view;
 
   template <typename T>
   struct wrap_operand<

include/sqlpp11/data_types/time_of_day.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/time_of_day/expression_operators.h>
 #include <sqlpp11/data_types/time_of_day/column_operators.h>
 #include <sqlpp11/data_types/time_of_day/parameter_value.h>
-#include <sqlpp11/data_types/time_of_day/result_field.h>

include/sqlpp11/data_types/time_of_day/data_type.h

@@ -35,6 +35,7 @@ namespace sqlpp
   {
     using _traits = make_traits<time_of_day, tag::is_value_type>;
     using _cpp_value_type = std::chrono::microseconds;
+    using _result_type = std::chrono::microseconds;
 
     template <typename T>
     using _is_valid_operand = is_time_of_day_t<T>;

include/sqlpp11/data_types/time_of_day/result_field.h

@@ -1,70 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2015-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/chrono.h>
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/time_of_day/data_type.h>
-#include <sqlpp11/field_spec.h>
-#include <ostream>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, time_of_day, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, time_of_day, CanBeNull>>
-  {
-    template <typename Target>
-    void _bind(Target& target, size_t i)
-    {
-      target._bind_time_of_day_result(i, &this->_value, &this->_is_null);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t i)
-    {
-      target._post_bind_time_of_day_result(i, &this->_value, &this->_is_null);
-    }
-  };
-
-  template <typename Db, typename NameType, bool CanBeNull>
-  inline std::ostream& operator<<(
-      std::ostream& os, const result_field_t<Db, field_spec_t<NameType, time_of_day, CanBeNull>>& e)
-  {
-    if (e.is_null())
-    {
-      os << "NULL";
-    }
-    else
-    {
-      os << ::date::make_time(e.value());
-    }
-    return os;
-  }
-}  // namespace sqlpp

include/sqlpp11/data_types/time_point.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/time_point/expression_operators.h>
 #include <sqlpp11/data_types/time_point/column_operators.h>
 #include <sqlpp11/data_types/time_point/parameter_value.h>
-#include <sqlpp11/data_types/time_point/result_field.h>

include/sqlpp11/data_types/time_point/data_type.h

@@ -35,6 +35,7 @@ namespace sqlpp
   {
     using _traits = make_traits<time_point, tag::is_value_type>;
     using _cpp_value_type = ::sqlpp::chrono::microsecond_point;
+    using _result_type = ::sqlpp::chrono::microsecond_point;
 
     template <typename T>
     using _is_valid_operand = is_day_or_time_point_t<T>;

include/sqlpp11/data_types/time_point/result_field.h

@@ -1,73 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2015-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/chrono.h>
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/time_point/data_type.h>
-#include <sqlpp11/field_spec.h>
-#include <ostream>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, time_point, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, time_point, CanBeNull>>
-  {
-    template <typename Target>
-    void _bind(Target& target, size_t i)
-    {
-      target._bind_date_time_result(i, &this->_value, &this->_is_null);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t i)
-    {
-      target._post_bind_date_time_result(i, &this->_value, &this->_is_null);
-    }
-  };
-
-  template <typename Db, typename NameType, bool CanBeNull>
-  inline std::ostream& operator<<(
-      std::ostream& os, const result_field_t<Db, field_spec_t<NameType, time_point, CanBeNull>>& e)
-  {
-    if (e.is_null())
-    {
-      os << "NULL";
-    }
-    else
-    {
-      const auto dp = ::sqlpp::chrono::floor<::date::days>(e.value());
-      const auto time = ::date::make_time(e.value() - dp);
-      const auto ymd = ::date::year_month_day{dp};
-      os << ymd << 'T' << time;
-    }
-    return os;
-  }
-}  // namespace sqlpp

include/sqlpp11/data_types/unsigned_integral.h

@@ -32,4 +32,3 @@
 #include <sqlpp11/data_types/unsigned_integral/expression_operators.h>
 #include <sqlpp11/data_types/unsigned_integral/column_operators.h>
 #include <sqlpp11/data_types/unsigned_integral/parameter_value.h>
-#include <sqlpp11/data_types/unsigned_integral/result_field.h>

include/sqlpp11/data_types/unsigned_integral/data_type.h

@@ -34,6 +34,7 @@ namespace sqlpp
   {
     using _traits = make_traits<unsigned_integral, tag::is_value_type>;
     using _cpp_value_type = uint64_t;
+    using _result_type = uint64_t;
 
     template <typename T>
     using _is_valid_operand = is_numeric_t<T>;

include/sqlpp11/data_types/unsigned_integral/result_field.h

@@ -1,53 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2016, Roland Bock, Aaron Bishop
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/unsigned_integral/data_type.h>
-#include <sqlpp11/field_spec.h>
-
-namespace sqlpp
-{
-  template <typename Db, typename NameType, bool CanBeNull>
-  struct result_field_t<Db, field_spec_t<NameType, unsigned_integral, CanBeNull>>
-      : public result_field_base<Db, field_spec_t<NameType, unsigned_integral, CanBeNull>>
-  {
-    template <typename Target>
-    void _bind(Target& target, size_t index)
-    {
-      target._bind_unsigned_integral_result(index, &this->_value, &this->_is_null);
-    }
-
-    template <typename Target>
-    void _post_bind(Target& target, size_t index)
-    {
-      target._post_bind_unsigned_integral_result(index, &this->_value, &this->_is_null);
-    }
-  };
-}  // namespace sqlpp

include/sqlpp11/eval.h

@@ -44,7 +44,7 @@ namespace sqlpp
     using _name_type = alias::a_t::_alias_t;
     using _value_type = value_type_of<Expr>;
     using _field_spec = field_spec_t<_name_type, _value_type, true>;
-    using type = result_field_t<Db, _field_spec>;
+    using type = typename _field_spec::cpp_type;
   };
 
   template <typename Db,

include/sqlpp11/field_spec.h

@@ -28,6 +28,10 @@
 
 #include <sqlpp11/type_traits.h>
 
+#include <type_traits>
+
+#include <sqlpp11/compat/optional.h>
+
 namespace sqlpp
 {
   template <typename NameType, typename ValueType, bool CanBeNull>
@@ -39,6 +43,10 @@ namespace sqlpp
     using _nodes = detail::type_vector<>;
 
     using _alias_t = NameType;
+
+    using cpp_type = typename std::conditional<CanBeNull,
+                                               sqlpp::optional<typename ValueType::_result_type>,
+                                               typename ValueType::_result_type>::type;
   };
 
   template <typename Left, typename Right, typename Enable = void>

include/sqlpp11/mysql/bind_result.h

@@ -28,6 +28,9 @@
 
 #include <sqlpp11/chrono.h>
 #include <sqlpp11/exception.h>
+#include <sqlpp11/compat/optional.h>
+#include <sqlpp11/compat/string_view.h>
+#include <sqlpp11/compat/span.h>
 #include <sqlpp11/mysql/detail/prepared_statement_handle.h>
 #include <sqlpp11/mysql/sqlpp_mysql.h>
 
@@ -45,6 +48,7 @@ namespace sqlpp
     {
       std::shared_ptr<detail::prepared_statement_handle_t> _handle;
       void* _result_row_address{nullptr};
+      bool _require_bind = true;
 
     public:
       bind_result_t() = default;
@@ -79,17 +83,23 @@ namespace sqlpp
 
         if (&result_row != _result_row_address)
         {
-          result_row._bind(*this);  // sets row data to mysql bind data
-          bind_impl();              // binds mysql statement to data
+          result_row._bind_fields(*this);  // sets row data to mysql bind data
           _result_row_address = &result_row;
         }
+
+        if (_require_bind)
+        {
+          bind_impl();              // binds mysql statement to data
+          _require_bind = false;
+        }
+
         if (next_impl())
         {
           if (not result_row)
           {
             result_row._validate();
           }
-          result_row._post_bind(*this);  // translates bind_data to row data where required
+          result_row._read_fields(*this);  // translates bind_data to row data where required
         }
         else
         {
@@ -103,270 +113,289 @@ namespace sqlpp
         return !_handle or !*_handle;
       }
 
-      void _bind_boolean_result(size_t index, signed char* value, bool* is_null)
+      void bind_field(size_t index, bool& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding boolean result " << static_cast<void*>(value) << " at index: " << index
+          std::cerr << "MySQL debug: binding boolean result at index: " << index
                     << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = nullptr;
-        meta_data.is_null = is_null;
+        auto& buffer{_handle->result_buffers[index]};
+        new (&buffer._bool) bool{};
 
         MYSQL_BIND& param{_handle->result_params[index]};
         param.buffer_type = MYSQL_TYPE_TINY;
-        param.buffer = value;
-        param.buffer_length = sizeof(*value);
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
+        param.buffer = &buffer._bool;
+        param.buffer_length = sizeof(buffer._bool);
+        param.length = &buffer.length;
+        param.is_null = &buffer.is_null;
         param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        param.error = &buffer.error;
       }
 
-      void _bind_integral_result(size_t index, int64_t* value, bool* is_null)
+      void bind_field(size_t index, int64_t& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding integral result " << static_cast<void*>(value) << " at index: " << index
+          std::cerr << "MySQL debug: binding integral result at index: " << index
                     << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = nullptr;
-        meta_data.is_null = is_null;
+        auto& buffer{_handle->result_buffers[index]};
+        new (&buffer._int64) int64_t{};
 
         MYSQL_BIND& param{_handle->result_params[index]};
         param.buffer_type = MYSQL_TYPE_LONGLONG;
-        param.buffer = value;
-        param.buffer_length = sizeof(*value);
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
+        param.buffer = &buffer._int64;
+        param.buffer_length = sizeof(buffer._int64);
+        param.length = &buffer.length;
+        param.is_null = &buffer.is_null;
         param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        param.error = &buffer.error;
       }
 
-      void _bind_unsigned_integral_result(size_t index, uint64_t* value, bool* is_null)
+      void bind_field(size_t index, uint64_t& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding unsigned integral result " << static_cast<void*>(value)
-                    << " at index: " << index << std::endl;
+          std::cerr << "MySQL debug: binding unsigned integral result at index: " << index << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = nullptr;
-        meta_data.is_null = is_null;
+        auto& buffer{_handle->result_buffers[index]};
+        new (&buffer._uint64) uint64_t{};
 
         MYSQL_BIND& param{_handle->result_params[index]};
         param.buffer_type = MYSQL_TYPE_LONGLONG;
-        param.buffer = value;
-        param.buffer_length = sizeof(*value);
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
+        param.buffer = &buffer._uint64;
+        param.buffer_length = sizeof(buffer._uint64);
+        param.length = &buffer.length;
+        param.is_null = &buffer.is_null;
         param.is_unsigned = true;
-        param.error = &meta_data.bound_error;
+        param.error = &buffer.error;
       }
 
-      void _bind_floating_point_result(size_t index, double* value, bool* is_null)
+      void bind_field(size_t index, double& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding floating point result " << static_cast<void*>(value)
-                    << " at index: " << index << std::endl;
+          std::cerr << "MySQL debug: binding floating point result at index: " << index << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = nullptr;
-        meta_data.is_null = is_null;
+        auto& buffer{_handle->result_buffers[index]};
+        new (&buffer._double) double{};
 
         MYSQL_BIND& param{_handle->result_params[index]};
         param.buffer_type = MYSQL_TYPE_DOUBLE;
-        param.buffer = value;
-        param.buffer_length = sizeof(*value);
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
+        param.buffer = &buffer._double;
+        param.buffer_length = sizeof(buffer._double);
+        param.length = &buffer.length;
+        param.is_null = &buffer.is_null;
         param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        param.error = &buffer.error;
       }
 
-      void _bind_text_result(size_t index, const char** value, size_t* len)
+      void bind_field(size_t index, sqlpp::string_view& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding text result " << static_cast<const void*>(*value) << " at index: " << index
+          std::cerr << "MySQL debug: binding text result at index: " << index
                     << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = len;
-        meta_data.is_null = nullptr;
-        meta_data.text_buffer = value;
-        if (meta_data.bound_text_buffer.empty())
-          meta_data.bound_text_buffer.resize(8);
+        auto& buffer{_handle->result_buffers[index]};
 
         MYSQL_BIND& param{_handle->result_params[index]};
         param.buffer_type = MYSQL_TYPE_STRING;
-        param.buffer = meta_data.bound_text_buffer.data();
-        param.buffer_length = meta_data.bound_text_buffer.size();
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
+        param.buffer = buffer.var_buffer.data();
+        param.buffer_length = buffer.var_buffer.size();
+        param.length = &buffer.length;
+        param.is_null = &buffer.is_null;
         param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        param.error = &buffer.error;
       }
-      void _bind_blob_result(size_t index, const char** value, size_t* len)
+
+      void bind_field(size_t index, sqlpp::span<uint8_t>& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding text result " << static_cast<const void*>(*value) << " at index: " << index
+          std::cerr << "MySQL debug: binding blob result at index: " << index
                     << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = len;
-        meta_data.is_null = nullptr;
-        meta_data.text_buffer = value;
-        if (meta_data.bound_text_buffer.empty())
-          meta_data.bound_text_buffer.resize(8);
+        auto& buffer{_handle->result_buffers[index]};
 
         MYSQL_BIND& param{_handle->result_params[index]};
         param.buffer_type = MYSQL_TYPE_BLOB;
-        param.buffer = meta_data.bound_text_buffer.data();
-        param.buffer_length = meta_data.bound_text_buffer.size();
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
+        param.buffer = buffer.var_buffer.data();
+        param.buffer_length = buffer.var_buffer.size();
+        param.length = &buffer.length;
+        param.is_null = &buffer.is_null;
         param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        param.error = &buffer.error;
       }
 
-      void _bind_date_result(size_t index, ::sqlpp::chrono::day_point* value, bool* is_null)
+      void bind_chrono_field(size_t index, enum_field_types buffer_type)
       {
-        if (_handle->debug)
-          std::cerr << "MySQL debug: binding date result " << static_cast<void*>(value) << " at index: " << index
-                    << std::endl;
-
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = nullptr;
-        meta_data.is_null = is_null;
-        meta_data.text_buffer = nullptr;
-        meta_data.bound_text_buffer.resize(sizeof(MYSQL_TIME));
+        auto& buffer{_handle->result_buffers[index]};
+        new (&buffer._mysql_time) MYSQL_TIME{};
 
         MYSQL_BIND& param{_handle->result_params[index]};
-        param.buffer_type = MYSQL_TYPE_DATE;
-        param.buffer = meta_data.bound_text_buffer.data();
-        param.buffer_length = meta_data.bound_text_buffer.size();
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
+        param.buffer_type = buffer_type;
+        param.buffer = &buffer._mysql_time;
+        param.buffer_length = sizeof(buffer._mysql_time);
+        param.length = &buffer.length;
+        param.is_null = &buffer.is_null;
         param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        param.error = &buffer.error;
       }
 
-      void _bind_date_time_result(size_t index, ::sqlpp::chrono::microsecond_point* value, bool* is_null)
+      void bind_field(size_t index, ::sqlpp::chrono::day_point& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding date time result " << static_cast<void*>(value) << " at index: " << index
+          std::cerr << "MySQL debug: binding date result at index: " << index
                     << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = nullptr;
-        meta_data.is_null = is_null;
-        meta_data.text_buffer = nullptr;
-        meta_data.bound_text_buffer.resize(sizeof(MYSQL_TIME));
-
-        MYSQL_BIND& param{_handle->result_params[index]};
-        param.buffer_type = MYSQL_TYPE_DATETIME;
-        param.buffer = meta_data.bound_text_buffer.data();
-        param.buffer_length = meta_data.bound_text_buffer.size();
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
-        param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        bind_chrono_field(index, MYSQL_TYPE_DATE);
       }
 
-      void _bind_time_of_day_result(size_t index, ::std::chrono::microseconds* value, bool* is_null)
+      void bind_field(size_t index, ::sqlpp::chrono::microsecond_point& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: binding time of day result " << static_cast<void*>(value) << " at index: " << index
+          std::cerr << "MySQL debug: binding date time result at index: " << index
                     << std::endl;
 
-        detail::result_meta_data_t& meta_data{_handle->result_param_meta_data[index]};
-        meta_data.index = index;
-        meta_data.len = nullptr;
-        meta_data.is_null = is_null;
-        meta_data.text_buffer = nullptr;
-        meta_data.bound_text_buffer.resize(sizeof(MYSQL_TIME));
-
-        MYSQL_BIND& param{_handle->result_params[index]};
-        param.buffer_type = MYSQL_TYPE_TIME;
-        param.buffer = meta_data.bound_text_buffer.data();
-        param.buffer_length = meta_data.bound_text_buffer.size();
-        param.length = &meta_data.bound_len;
-        param.is_null = &meta_data.bound_is_null;
-        param.is_unsigned = false;
-        param.error = &meta_data.bound_error;
+        bind_chrono_field(index, MYSQL_TYPE_DATETIME);
       }
 
-      void _post_bind_boolean_result(size_t /* index */, signed char* /* value */, bool* /* is_null */)
-      {
-      }
-      void _post_bind_floating_point_result(size_t /* index */, double* /* value */, bool* /* is_null */)
-      {
-      }
-      void _post_bind_integral_result(size_t /* index */, int64_t* /* value */, bool* /* is_null */)
-      {
-      }
-      void _post_bind_unsigned_integral_result(size_t /* index */, uint64_t* /* value */, bool* /* is_null */)
-      {
-      }
-      void _post_bind_text_result(size_t /* index */, const char** /* text */, size_t* /* len */)
-      {
-      }
-      void _post_bind_date_result(size_t index, ::sqlpp::chrono::day_point* value, bool* is_null)
+      void bind_field(size_t index, ::std::chrono::microseconds& /*value*/)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: post binding date result " << static_cast<void*>(value) << " at index: " << index
+          std::cerr << "MySQL debug: binding time of day result at index: " << index
                     << std::endl;
 
-        if (not *is_null)
+        bind_chrono_field(index, MYSQL_TYPE_TIME);
+      }
+
+      template <class T>
+      void bind_field(size_t index, sqlpp::optional<T>& value)
+      {
+        value = T{};
+        bind_field(index, *value);
+      }
+
+      void read_field(size_t index, bool& value)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: reading bool result at index: " << index
+                    << std::endl;
+        value = _handle->result_buffers[index]._bool;
+      }
+
+      void read_field(size_t index, int64_t& value)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: reading integral result at index: " << index
+                    << std::endl;
+        value = _handle->result_buffers[index]._int64;
+      }
+
+      void read_field(size_t index, uint64_t& value)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: reading unsigned integral result at index: " << index
+                    << std::endl;
+        value = _handle->result_buffers[index]._uint64;
+      }
+
+      void read_field(size_t index, double& value)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: reading floating point result at index: " << index
+                    << std::endl;
+        value = _handle->result_buffers[index]._double;
+      }
+
+      void refetch_if_required(size_t index)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: Checking result size at index: " << index
+                    << std::endl;
+        auto& buffer = _handle->result_buffers[index];
+        auto& params = _handle->result_params[index];
+        if (*params.length > params.buffer_length)
         {
-          const auto& dt =
-              *reinterpret_cast<const MYSQL_TIME*>(_handle->result_param_meta_data[index].bound_text_buffer.data());
-          if (dt.year > std::numeric_limits<int>::max())
-            throw sqlpp::exception{"cannot read year from db: " + std::to_string(dt.year)};
-          *is_null = false;
-          *value = ::date::year(static_cast<int>(dt.year)) / ::date::month(dt.month) / ::date::day(dt.day);
+          if (_handle->debug)
+            std::cerr << "MySQL debug: increasing buffer at: " << index << " to " << *params.length << std::endl;
+          buffer.var_buffer.resize(*params.length);
+          params.buffer = buffer.var_buffer.data();
+          params.buffer_length = buffer.var_buffer.size();
+          const auto err = mysql_stmt_fetch_column(_handle->mysql_stmt, &params, index, 0);
+          if (err)
+            throw sqlpp::exception{std::string{"MySQL: Fetch column after reallocate failed: "} + "error-code: " +
+                                   std::to_string(err) + ", stmt-error: " + mysql_stmt_error(_handle->mysql_stmt) +
+                                   ", stmt-errno: " + std::to_string(mysql_stmt_errno(_handle->mysql_stmt))};
+          _require_bind = true;
         }
       }
 
-      void _post_bind_date_time_result(size_t index, ::sqlpp::chrono::microsecond_point* value, bool* is_null)
+      void read_field(size_t index, sqlpp::string_view& value)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: post binding date time result " << static_cast<void*>(value) << " at index: " << index
+          std::cerr << "MySQL debug: reading text result at index: " << index
                     << std::endl;
-
-        if (not *is_null)
-        {
-          const auto& dt =
-              *reinterpret_cast<const MYSQL_TIME*>(_handle->result_param_meta_data[index].bound_text_buffer.data());
-          if (dt.year > std::numeric_limits<int>::max())
-            throw sqlpp::exception{"cannot read year from db: " + std::to_string(dt.year)};
-          *is_null = false;
-          *value = ::sqlpp::chrono::day_point(::date::year(static_cast<int>(dt.year)) / ::date::month(dt.month) / ::date::day(dt.day)) +
-                   std::chrono::hours(dt.hour) + std::chrono::minutes(dt.minute) + std::chrono::seconds(dt.second) +
-                   std::chrono::microseconds(dt.second_part);
-        }
+        refetch_if_required(index);
+        const auto& buffer = _handle->result_buffers[index];
+        const auto& params = _handle->result_params[index];
+        value = sqlpp::string_view(buffer.var_buffer.data(), *params.length);
       }
 
-      void _post_bind_time_of_day_result(size_t index, ::std::chrono::microseconds* value, bool* is_null)
+      void read_field(size_t index, sqlpp::span<uint8_t>& value)
       {
         if (_handle->debug)
-          std::cerr << "MySQL debug: post binding date time result " << static_cast<void*>(value) << " at index: " << index
+          std::cerr << "MySQL debug: reading blob result at index: " << index
+                    << std::endl;
+         refetch_if_required(index);
+        const auto& buffer = _handle->result_buffers[index];
+        const auto& params = _handle->result_params[index];
+        value = sqlpp::span<uint8_t>(reinterpret_cast<const uint8_t*>(buffer.var_buffer.data()), *params.length);
+      }
+
+      void read_field(size_t index, ::sqlpp::chrono::day_point& value)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: reading date result at index: " << index
                     << std::endl;
 
-        if (not *is_null)
+        const auto& dt = _handle->result_buffers[index]._mysql_time;
+        if (dt.year > std::numeric_limits<int>::max())
+          throw sqlpp::exception{"cannot read year from db: " + std::to_string(dt.year)};
+        value = ::date::year(static_cast<int>(dt.year)) / ::date::month(dt.month) / ::date::day(dt.day);
+      }
+
+      void read_field(size_t index, ::sqlpp::chrono::microsecond_point& value)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: reading date time result at index: " << index << std::endl;
+
+        const auto& dt = _handle->result_buffers[index]._mysql_time;
+        if (dt.year > std::numeric_limits<int>::max())
+          throw sqlpp::exception{"cannot read year from db: " + std::to_string(dt.year)};
+        value = ::sqlpp::chrono::day_point(::date::year(static_cast<int>(dt.year)) / ::date::month(dt.month) /
+                                            ::date::day(dt.day)) +
+                 std::chrono::hours(dt.hour) + std::chrono::minutes(dt.minute) + std::chrono::seconds(dt.second) +
+                 std::chrono::microseconds(dt.second_part);
+      }
+
+      void read_field(size_t index, ::std::chrono::microseconds& value)
+      {
+        if (_handle->debug)
+          std::cerr << "MySQL debug: reading date time result at index: " << index << std::endl;
+
+        const auto& dt = _handle->result_buffers[index]._mysql_time;
+        value = std::chrono::hours(dt.hour) + std::chrono::minutes(dt.minute) + std::chrono::seconds(dt.second) +
+                std::chrono::microseconds(dt.second_part);
+      }
+
+      template <class T>
+      void read_field(size_t index, sqlpp::optional<T>& value)
+      {
+        if (_handle->result_buffers[index].is_null)
         {
-          const auto& dt =
-              *reinterpret_cast<const MYSQL_TIME*>(_handle->result_param_meta_data[index].bound_text_buffer.data());
-          *value = std::chrono::hours(dt.hour) + std::chrono::minutes(dt.minute) + std::chrono::seconds(dt.second) +
-                   std::chrono::microseconds(dt.second_part);
+          value.reset();
+          return;
         }
+        if (!value)
+          value = T{};
+        read_field(index, *value);
       }
 
     private:
@@ -387,58 +416,12 @@ namespace sqlpp
         if (_handle->debug)
           std::cerr << "MySQL debug: Accessing next row of handle at " << _handle.get() << std::endl;
 
-        auto flag = mysql_stmt_fetch(_handle->mysql_stmt);
+        const auto flag = mysql_stmt_fetch(_handle->mysql_stmt);
 
         switch (flag)
         {
           case 0:
           case MYSQL_DATA_TRUNCATED:
-          {
-            bool need_to_rebind{false};
-            for (auto& r : _handle->result_param_meta_data)
-            {
-              if (r.len)
-              {
-                if (r.bound_is_null)
-                {
-                  *r.text_buffer = nullptr;
-                  *r.len = 0;
-                }
-                else
-                {
-                  if (r.bound_len > r.bound_text_buffer.size())
-                  {
-                    if (_handle->debug)
-                      std::cerr << "MySQL debug: Need to reallocate buffer " << static_cast<const void*>(*r.text_buffer)
-                                << " at index " << r.index << " for handle at " << _handle.get() << std::endl;
-                    need_to_rebind = true;
-                    r.bound_text_buffer.resize(r.bound_len);
-                    MYSQL_BIND& param{_handle->result_params[r.index]};
-                    param.buffer = r.bound_text_buffer.data();
-                    param.buffer_length = r.bound_text_buffer.size();
-
-                    auto err =
-                        mysql_stmt_fetch_column(_handle->mysql_stmt, &param, static_cast<unsigned int>(r.index), 0);
-                    if (err)
-                      throw sqlpp::exception{std::string{"MySQL: Fetch column after reallocate failed: "} +
-                                             "error-code: " + std::to_string(err) +
-                                             ", stmt-error: " + mysql_stmt_error(_handle->mysql_stmt) +
-                                             ", stmt-errno: " + std::to_string(mysql_stmt_errno(_handle->mysql_stmt))};
-                  }
-                  *r.text_buffer = r.bound_text_buffer.data();
-                  if (_handle->debug)
-                    std::cerr << "MySQL debug: New buffer " << static_cast<const void*>(*r.text_buffer) << " at index "
-                              << r.index << " for handle at " << _handle.get() << std::endl;
-
-                  *r.len = r.bound_len;
-                }
-              }
-              if (r.is_null)
-                *r.is_null = r.bound_is_null;
-            }
-            if (need_to_rebind)
-              bind_impl();
-          }
             return true;
           case 1:
             throw sqlpp::exception{std::string{"MySQL: Could not fetch next result: "} +

include/sqlpp11/mysql/char_result.h

@@ -36,6 +36,9 @@
 #include <sqlpp11/mysql/detail/result_handle.h>
 #include <sqlpp11/mysql/sqlpp_mysql.h>
 #include <sqlpp11/mysql/char_result_row.h>
+#include <sqlpp11/compat/optional.h>
+#include <sqlpp11/compat/string_view.h>
+#include <sqlpp11/compat/span.h>
 
 namespace sqlpp
 {
@@ -88,7 +91,7 @@ namespace sqlpp
           {
             result_row._validate();
           }
-          result_row._bind(*this);
+          result_row._read_fields(*this);
         }
         else
         {
@@ -102,114 +105,102 @@ namespace sqlpp
         return !_handle or !*_handle;
       }
 
-      void _bind_boolean_result(size_t index, signed char* value, bool* is_null)
+      void read_field(size_t index, bool& value)
       {
-        *is_null = (_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr);
-        *value =
-            (*is_null ? false : (_char_result_row.data[index][0] == 't' or _char_result_row.data[index][0] == '1'));
+        value = (_char_result_row.data[index][0] == 't' or _char_result_row.data[index][0] == '1');
       }
 
-      void _bind_floating_point_result(size_t index, double* value, bool* is_null)
+      void read_field(size_t index, double& value)
       {
-        *is_null = (_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr);
-        *value = (*is_null ? 0 : std::strtod(_char_result_row.data[index], nullptr));
+        value = std::strtod(_char_result_row.data[index], nullptr);
       }
 
-      void _bind_integral_result(size_t index, int64_t* value, bool* is_null)
+      void read_field(size_t index, int64_t& value)
       {
-        *is_null = (_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr);
-        *value = (*is_null ? 0 : std::strtoll(_char_result_row.data[index], nullptr, 10));
+        value = std::strtoll(_char_result_row.data[index], nullptr, 10);
       }
 
-      void _bind_unsigned_integral_result(size_t index, uint64_t* value, bool* is_null)
+      void read_field(size_t index, uint64_t& value)
       {
-        *is_null = (_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr);
-        *value = (*is_null ? 0 : std::strtoull(_char_result_row.data[index], nullptr, 10));
+        value = std::strtoull(_char_result_row.data[index], nullptr, 10);
       }
 
-      void _bind_blob_result(size_t index, const uint8_t** value, size_t* len)
+      void read_field(size_t index, sqlpp::span<uint8_t>& value)
       {
-        bool is_null{_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr};
-        *value = (uint8_t*)(is_null ? nullptr : _char_result_row.data[index]);
-        *len = (is_null ? 0 : _char_result_row.len[index]);
+        value = sqlpp::span<uint8_t>(reinterpret_cast<const uint8_t*>(_char_result_row.data[index]), _char_result_row.len[index]);
       }
 
-      void _bind_text_result(size_t index, const char** value, size_t* len)
+      void read_field(size_t index, sqlpp::string_view& value)
       {
-        bool is_null{_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr};
-        *value = (is_null ? nullptr : _char_result_row.data[index]);
-        *len = (is_null ? 0 : _char_result_row.len[index]);
+        value = sqlpp::string_view(_char_result_row.data[index], _char_result_row.len[index]);
       }
 
-      void _bind_date_result(size_t index, ::sqlpp::chrono::day_point* value, bool* is_null)
+      void read_field(size_t index, ::sqlpp::chrono::day_point& value)
       {
         if (_handle->debug)
           std::cerr << "MySQL debug: parsing date result at index: " << index << std::endl;
 
-        *value = {};
-        *is_null = (_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr);
-        if (*is_null)
-        {
-          return;
-        }
-
         const auto date_string = _char_result_row.data[index];
         if (_handle->debug)
           std::cerr << "MySQL debug: date string: " << date_string << std::endl;
 
-        if (::sqlpp::detail::parse_date(*value, date_string) == false)
+        if (::sqlpp::detail::parse_date(value, date_string) == false)
         {
           if (_handle->debug)
             std::cerr << "MySQL debug: invalid date result: " << date_string << std::endl;
         }
       }
 
-      void _bind_date_time_result(size_t index, ::sqlpp::chrono::microsecond_point* value, bool* is_null)
+      void read_field(size_t index, ::sqlpp::chrono::microsecond_point& value)
       {
         if (_handle->debug)
           std::cerr << "MySQL debug: parsing date result at index: " << index << std::endl;
 
-        *value = {};
-        *is_null = (_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr);
-        if (*is_null)
-        {
-          return;
-        }
-
         const auto date_time_string = _char_result_row.data[index];
         if (_handle->debug)
           std::cerr << "MySQL debug: date_time string: " << date_time_string << std::endl;
 
-        if (::sqlpp::detail::parse_timestamp(*value, date_time_string) == false)
+        if (::sqlpp::detail::parse_timestamp(value, date_time_string) == false)
         {
           if (_handle->debug)
             std::cerr << "MySQL debug: invalid date_time result: " << date_time_string << std::endl;
         }
       }
 
-      void _bind_time_of_day_result(size_t index, ::std::chrono::microseconds* value, bool* is_null)
+      void read_field(size_t index, ::std::chrono::microseconds& value)
       {
         if (_handle->debug)
           std::cerr << "MySQL debug: parsing time of day result at index: " << index << std::endl;
 
-        *value = {};
-        *is_null = (_char_result_row.data == nullptr or _char_result_row.data[index] == nullptr);
-        if (*is_null)
-        {
-          return;
-        }
-
         const auto time_string = _char_result_row.data[index];
         if (_handle->debug)
           std::cerr << "MySQL debug: time of day string: " << time_string << std::endl;
 
-        if (::sqlpp::detail::parse_time_of_day(*value, time_string) == false)
+        if (::sqlpp::detail::parse_time_of_day(value, time_string) == false)
         {
           if (_handle->debug)
             std::cerr << "MySQL debug: invalid time result: " << time_string << std::endl;
         }
       }
 
+      template <typename T>
+      auto read_field(size_t index, sqlpp::optional<T>& value) -> void
+      {
+        const bool is_null = _char_result_row.data[index] == nullptr;
+        if (is_null)
+        {
+          value.reset();
+        }
+        else
+        {
+          if (not value)
+          {
+            value = T{};
+          }
+          read_field(index, *value);
+        }
+      }
+
     private:
       bool next_impl()
       {

include/sqlpp11/mysql/detail/prepared_statement_handle.h

@@ -36,16 +36,20 @@ namespace sqlpp
   {
     namespace detail
     {
-      struct result_meta_data_t
+      struct bind_result_buffer
       {
-        size_t index;
-        unsigned long bound_len;
-        my_bool bound_is_null;
-        my_bool bound_error;
-        std::vector<char> bound_text_buffer;  // also for blobs
-        const char** text_buffer;
-        size_t* len;
-        bool* is_null;
+        unsigned long length;
+        my_bool is_null;
+        my_bool error;
+        union // unnamed union injects members into scope
+        {
+          bool _bool;
+          int64_t _int64;
+          uint64_t _uint64;
+          double _double;
+          MYSQL_TIME _mysql_time;
+        };
+        std::vector<char> var_buffer;  // text and blobs
       };
 
       struct prepared_statement_handle_t
@@ -72,7 +76,7 @@ namespace sqlpp
         std::vector<MYSQL_TIME> stmt_date_time_param_buffer;
         std::vector<wrapped_bool> stmt_param_is_null;  // my_bool is bool after 8.0, and vector<bool> is bad
         std::vector<MYSQL_BIND> result_params;
-        std::vector<result_meta_data_t> result_param_meta_data;
+        std::vector<bind_result_buffer> result_buffers;
         bool debug;
 
         prepared_statement_handle_t(MYSQL_STMT* stmt, size_t no_of_parameters, size_t no_of_columns, bool debug_)
@@ -81,7 +85,7 @@ namespace sqlpp
               stmt_date_time_param_buffer(no_of_parameters, MYSQL_TIME{}),  // ()-init for correct constructor
               stmt_param_is_null(no_of_parameters, false),                  // ()-init for correct constructor
               result_params(no_of_columns, MYSQL_BIND{}),                   // ()-init for correct constructor
-              result_param_meta_data(no_of_columns, result_meta_data_t{}),  // ()-init for correct constructor
+              result_buffers(no_of_columns, bind_result_buffer{}),  // ()-init for correct constructor
               debug{debug_}
         {
         }

include/sqlpp11/postgresql/bind_result.h

@@ -30,6 +30,9 @@
 #include <sqlpp11/chrono.h>
 #include <sqlpp11/data_types.h>
 #include <sqlpp11/detail/parse_date_time.h>
+#include <sqlpp11/compat/optional.h>
+#include <sqlpp11/compat/string_view.h>
+#include <sqlpp11/compat/span.h>
 
 #include <iomanip>
 #include <iostream>
@@ -49,10 +52,63 @@ namespace sqlpp
     namespace detail
     {
       struct statement_handle_t;
-    }
+
+      inline unsigned char unhex(unsigned char c)
+      {
+        switch (c)
+        {
+          case '0':
+          case '1':
+          case '2':
+          case '3':
+          case '4':
+          case '5':
+          case '6':
+          case '7':
+          case '8':
+          case '9':
+            return c - '0';
+          case 'a':
+          case 'b':
+          case 'c':
+          case 'd':
+          case 'e':
+          case 'f':
+            return c + 10 - 'a';
+          case 'A':
+          case 'B':
+          case 'C':
+          case 'D':
+          case 'E':
+          case 'F':
+            return c + 10 - 'A';
+        }
+        throw sqlpp::exception{std::string{"Unexpected hex char: "} + static_cast<char>(c)};
+      }
+
+      inline size_t hex_assign(std::vector<uint8_t>& value, const uint8_t* blob, size_t len)
+      {
+        const auto result_size = len / 2 - 1;  // unhex - leading chars
+        if (value.size() < result_size)
+        {
+          value.resize(result_size);  // unhex - leading chars
+        }
+        size_t val_index = 0;
+        size_t blob_index = 2;
+        while (blob_index < len)
+        {
+          value[val_index] = static_cast<unsigned char>(unhex(blob[blob_index]) << 4) + unhex(blob[blob_index + 1]);
+          ++val_index;
+          blob_index += 2;
+        }
+        return result_size;
+      }
+    }  // namespace detail
 
     class bind_result_t
     {
+      // Need to buffer blobs (or switch to PQexecParams with binary results)
+      std::vector<std::vector<uint8_t>> _var_buffers;
     private:
       std::shared_ptr<detail::statement_handle_t> _handle;
 
@@ -97,9 +153,9 @@ namespace sqlpp
 
       bind_result_t(const std::shared_ptr<detail::statement_handle_t>& handle) : _handle(handle)
       {
+        _var_buffers.resize(_handle->result.field_count());
         if (this->_handle && this->_handle->debug())
         {
-          // cerr
           std::cerr << "PostgreSQL debug: constructing bind result, using handle at: " << this->_handle.get()
                     << std::endl;
         }
@@ -131,7 +187,7 @@ namespace sqlpp
           {
             result_row._validate();
           }
-          result_row._bind(*this);
+          result_row._read_fields(*this);
         }
         else
         {
@@ -142,72 +198,60 @@ namespace sqlpp
         }
       }
 
-      void _bind_boolean_result(size_t _index, signed char* value, bool* is_null)
+      void read_field(size_t _index, bool& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding boolean result at index: " << index << std::endl;
+          std::cerr << "PostgreSQL debug: reading boolean result at index: " << index << std::endl;
         }
 
-        *is_null = _handle->result.is_null(_handle->count, index);
-        *value = _handle->result.get_bool_value(_handle->count, index);
+        value = _handle->result.get_bool_value(_handle->count, index);
       }
 
-      void _bind_floating_point_result(size_t _index, double* value, bool* is_null)
+      void read_field(size_t _index, double& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding floating_point result at index: " << index << std::endl;
+          std::cerr << "PostgreSQL debug: reading floating_point result at index: " << index << std::endl;
         }
 
-        *is_null = _handle->result.is_null(_handle->count, index);
-        *value = _handle->result.get_double_value(_handle->count, index);
+        value = _handle->result.get_double_value(_handle->count, index);
       }
 
-      void _bind_integral_result(size_t _index, int64_t* value, bool* is_null)
+      void read_field(size_t _index, int64_t& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding integral result at index: " << index << std::endl;
+          std::cerr << "PostgreSQL debug: reading integral result at index: " << index << std::endl;
         }
 
-        *is_null = _handle->result.is_null(_handle->count, index);
-        *value = _handle->result.get_int64_value(_handle->count, index);
+        value = _handle->result.get_int64_value(_handle->count, index);
       }
 
-      void _bind_unsigned_integral_result(size_t _index, uint64_t* value, bool* is_null)
+      void read_field(size_t _index, uint64_t& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding unsigned integral result at index: " << index << std::endl;
+          std::cerr << "PostgreSQL debug: reading unsigned integral result at index: " << index << std::endl;
         }
 
-        *is_null = _handle->result.is_null(_handle->count, index);
-        *value = _handle->result.get_uint64_value(_handle->count, index);
+        value = _handle->result.get_uint64_value(_handle->count, index);
       }
 
-      void _bind_text_result(size_t _index, const char** value, size_t* len)
+      void read_field(size_t _index, sqlpp::string_view& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding text result at index: " << index << std::endl;
+          std::cerr << "PostgreSQL debug: reading text result at index: " << index << std::endl;
         }
 
-        if (_handle->result.is_null(_handle->count, index))
-        {
-          *value = nullptr;
-          *len = 0;
-        }
-        else
-        {
-          *value = _handle->result.get_char_ptr_value(_handle->count, index);
-          *len = static_cast<size_t>(_handle->result.length(_handle->count, index));
-        }
+        value = sqlpp::string_view(_handle->result.get_char_ptr_value(_handle->count, index),
+                                   static_cast<size_t>(_handle->result.length(_handle->count, index)));
       }
 
       // PostgreSQL will return one of those (using the default ISO client):
@@ -218,20 +262,13 @@ namespace sqlpp
       // 1992-10-10 01:02:03-06:30 - for some timezones with non-hour offset
       // 1900-01-01 - date only
       // we do not support time-only values !
-      void _bind_date_result(size_t _index, ::sqlpp::chrono::day_point* value, bool* is_null)
+      void read_field(size_t _index, ::sqlpp::chrono::day_point& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
 
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding date result at index: " << index << std::endl;
-        }
-
-        *value = {};
-        *is_null = _handle->result.is_null(_handle->count, index);
-        if (*is_null)
-        {
-          return;
+          std::cerr << "PostgreSQL debug: reading date result at index: " << index << std::endl;
         }
 
         const auto date_string = _handle->result.get_char_ptr_value(_handle->count, index);
@@ -239,7 +276,7 @@ namespace sqlpp
         {
           std::cerr << "PostgreSQL debug: date string: " << date_string << std::endl;
         }
-        if (::sqlpp::detail::parse_date(*value, date_string) == false)
+        if (::sqlpp::detail::parse_date(value, date_string) == false)
         {
           if (_handle->debug())
           {
@@ -249,19 +286,12 @@ namespace sqlpp
       }
 
       // always returns UTC time for timestamp with time zone
-      void _bind_date_time_result(size_t _index, ::sqlpp::chrono::microsecond_point* value, bool* is_null)
+      void read_field(size_t _index, ::sqlpp::chrono::microsecond_point& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding date_time result at index: " << index << std::endl;
-        }
-
-        *value = {};
-        *is_null = _handle->result.is_null(_handle->count, index);
-        if (*is_null)
-        {
-          return;
+          std::cerr << "PostgreSQL debug: reading date_time result at index: " << index << std::endl;
         }
 
         const auto date_string = _handle->result.get_char_ptr_value(_handle->count, index);
@@ -269,7 +299,7 @@ namespace sqlpp
         {
           std::cerr << "PostgreSQL debug: got date_time string: " << date_string << std::endl;
         }
-        if (::sqlpp::detail::parse_timestamp(*value, date_string) == false)
+        if (::sqlpp::detail::parse_timestamp(value, date_string) == false)
         {
           if (_handle->debug())
           {
@@ -279,19 +309,12 @@ namespace sqlpp
       }
 
       // always returns UTC time for time with time zone
-      void _bind_time_of_day_result(size_t _index, ::std::chrono::microseconds* value, bool* is_null)
+      void read_field(size_t _index, ::std::chrono::microseconds& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding time result at index: " << index << std::endl;
-        }
-
-        *value = {};
-        *is_null = _handle->result.is_null(_handle->count, index);
-        if (*is_null)
-        {
-          return;
+          std::cerr << "PostgreSQL debug: reading time result at index: " << index << std::endl;
         }
 
         const auto time_string = _handle->result.get_char_ptr_value(_handle->count, index);
@@ -301,7 +324,7 @@ namespace sqlpp
           std::cerr << "PostgreSQL debug: got time string: " << time_string << std::endl;
         }
 
-        if (::sqlpp::detail::parse_time_of_day(*value, time_string) == false)
+        if (::sqlpp::detail::parse_time_of_day(value, time_string) == false)
         {
           if (_handle->debug()) {
             std::cerr << "PostgreSQL debug: got invalid time '" << time_string << "'" << std::endl;
@@ -309,23 +332,39 @@ namespace sqlpp
         }
       }
 
-      void _bind_blob_result(size_t _index, const uint8_t** value, size_t* len)
+      void read_field(size_t _index, sqlpp::span<uint8_t>& value)
       {
-        auto index = static_cast<int>(_index);
+        const auto index = static_cast<int>(_index);
         if (_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: binding blob result at index: " << index << std::endl;
+          std::cerr << "PostgreSQL debug: reading blob result at index: " << index << std::endl;
         }
 
+        // Need to decode the hex data.
+        // Using PQexecParams would allow to use binary data.
+        // That's certainly faster, but some effort to determine the correct column types.
+        const auto size =
+            detail::hex_assign(_var_buffers[_index], _handle->result.get_blob_value(_handle->count, index),
+                               static_cast<size_t>(_handle->result.length(_handle->count, index)));
+
+        value = sqlpp::span<uint8_t>(_var_buffers[_index].data(), size);
+      }
+
+      template <typename T>
+      auto read_field(size_t _index, sqlpp::optional<T>& value) -> void
+      {
+        const auto index = static_cast<int>(_index);
         if (_handle->result.is_null(_handle->count, index))
         {
-          *value = nullptr;
-          *len = 0;
+          value.reset();
         }
         else
         {
-          *value = _handle->result.get_blob_value(_handle->count, index);
-          *len   = static_cast<size_t>(_handle->result.length(_handle->count, index));
+          if (not value)
+          {
+            value = T{};
+          }
+          read_field(_index, *value);
         }
       }
 

include/sqlpp11/postgresql/connection.h

@@ -36,7 +36,6 @@
 #include <sqlpp11/connection.h>
 #include <sqlpp11/detail/float_safe_ostringstream.h>
 #include <sqlpp11/postgresql/bind_result.h>
-#include <sqlpp11/postgresql/result_field.h>
 #include <sqlpp11/postgresql/connection_config.h>
 #include <sqlpp11/postgresql/prepared_statement.h>
 #include <sqlpp11/postgresql/exception.h>

include/sqlpp11/postgresql/detail/prepared_statement_handle.h

@@ -141,8 +141,10 @@ namespace sqlpp
           valid = false;
           count = 0;
           total_count = 0;
-          result = PQexecPrepared(connection.native_handle(), _name.data(), static_cast<int>(size), values.data(), nullptr, nullptr, 0);
-                  /// @todo validate result? is it really valid
+          result = PQexecPrepared(connection.native_handle(), /*stmtName*/ _name.data(),
+                                  /*nParams*/ static_cast<int>(size), /*paramValues*/ values.data(),
+                                  /*paramLengths*/ nullptr, /*paramFormats*/ nullptr, /*resultFormat*/ 0);
+          /// @todo validate result? is it really valid
           valid = true;
         }
 
@@ -171,7 +173,8 @@ namespace sqlpp
         void prepare(const std::string& stmt)
         {
           // Create the prepared statement
-          result = PQprepare(connection.native_handle(), _name.c_str(), stmt.c_str(), 0, nullptr);
+          result = PQprepare(connection.native_handle(), _name.c_str(), stmt.c_str(),
+                                                       /*nParams*/ 0, /*paramTypes*/ nullptr);
           valid = true;
         }
       };

include/sqlpp11/postgresql/result.h

@@ -118,6 +118,7 @@ namespace sqlpp
         check_index(record, field);
         auto t = int64_t{};
         const auto txt = std::string{get_pq_value(m_result, record, field)};
+        std::cerr << "txt: " << txt << ", record: " << record << ", field: " << field << std::endl;
         if(txt != "")
         {
           t = std::stoll(txt);

include/sqlpp11/postgresql/result_field.h

@@ -1,120 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2021-2021, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/exception.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/result_field_base.h>
-#include <sqlpp11/data_types/blob/data_type.h>
-#include <sqlpp11/field_spec.h>
-#include <ostream>
-#include <string>
-
-namespace sqlpp
-{
-  namespace postgresql
-  {
-    // Forward declaration
-    class connection_base;
-  }
-
-  namespace detail
-  {
-    inline unsigned char unhex(unsigned char c)
-    {
-      switch (c)
-      {
-        case '0':
-        case '1':
-        case '2':
-        case '3':
-        case '4':
-        case '5':
-        case '6':
-        case '7':
-        case '8':
-        case '9':
-          return c - '0';
-        case 'a':
-        case 'b':
-        case 'c':
-        case 'd':
-        case 'e':
-        case 'f':
-          return c + 10 - 'a';
-        case 'A':
-        case 'B':
-        case 'C':
-        case 'D':
-        case 'E':
-        case 'F':
-          return c + 10 - 'A';
-      }
-      throw sqlpp::exception{std::string{"Unexpected hex char: "} + static_cast<char>(c)};
-    }
-
-    inline void hex_assign(std::vector<unsigned char>& value, const uint8_t* blob, size_t len)
-    {
-      value.resize(len / 2 - 1); // unhex - leading chars
-      size_t val_index = 0;
-      size_t blob_index = 2;
-      while (blob_index < len)
-      {
-        value[val_index] = static_cast<unsigned char>(unhex(blob[blob_index]) << 4) + unhex(blob[blob_index + 1]);
-        ++val_index;
-        blob_index += 2;
-      }
-    }
-  }  // namespace detail
-
-  template <typename NameType, bool CanBeNull>
-  struct result_field_t<postgresql::connection_base, field_spec_t<NameType, blob, CanBeNull>>
-      : public result_field_base<postgresql::connection_base, field_spec_t<NameType, blob, CanBeNull>>
-  {
-  private:
-    const uint8_t* _blob{nullptr};  // Non-owning
-
-  public:
-    size_t len{};
-
-    template <typename Target>
-    void _bind(Target& target, size_t index)
-    {
-      target._bind_blob_result(index, &_blob, &len);
-      if (_blob)
-      {
-        detail::hex_assign(this->_value, _blob, len);
-        len = this->_value.size();
-      }
-      else
-        this->_value.clear();
-      this->_is_null = (_blob == nullptr);
-    }
-
-  };
-}  // namespace sqlpp

include/sqlpp11/result_field.h

@@ -1,62 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <ostream>
-#include <sqlpp11/wrong.h>
-#include <sqlpp11/wrap_operand.h>
-#include <sqlpp11/type_traits.h>
-
-namespace sqlpp
-{
-  template <typename Db, typename FieldSpec>
-  struct result_field_t
-  {
-    using X = typename FieldSpec::incorrect;
-    static_assert(wrong_t<result_field_t>::value, "Missing specialization for result_field_t");
-  };
-
-  template <typename Context, typename Db, typename FieldSpec>
-  Context& serialize(const result_field_t<Db, FieldSpec>& t, Context& context)
-  {
-    if (t.is_null())
-    {
-      context << "NULL";
-    }
-    else
-    {
-      serialize(wrap_operand_t<cpp_value_type_of<FieldSpec>>(t.value()), context);
-    }
-    return context;
-  }
-
-  template <typename Db, typename FieldSpec>
-  inline std::ostream& operator<<(std::ostream& os, const result_field_t<Db, FieldSpec>& rf)
-  {
-    return serialize(rf, os);
-  }
-}  // namespace sqlpp

include/sqlpp11/result_field_base.h

@@ -1,111 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2016, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/alias_operators.h>
-#include <sqlpp11/basic_expression_operators.h>
-#include <sqlpp11/exception.h>
-#include <sqlpp11/result_field.h>
-#include <sqlpp11/type_traits.h>
-#include <utility>
-
-namespace sqlpp
-{
-  template <typename Db, typename FieldSpec, typename StorageType = typename value_type_of<FieldSpec>::_cpp_value_type>
-  struct result_field_base
-  {
-    using _field_spec_t = FieldSpec;
-    using _alias_t = typename FieldSpec::_alias_t;
-    using _cpp_value_type = typename value_type_of<FieldSpec>::_cpp_value_type;
-    using _cpp_storage_type = StorageType;
-
-    using _traits = make_traits<value_type_of<_field_spec_t>,
-                                tag::is_result_field,
-                                tag::is_expression>;
-
-    using _nodes = detail::type_vector<>;
-    using _can_be_null = column_spec_can_be_null_t<_field_spec_t>;
-
-    result_field_base() : _is_valid{false}, _is_null{true}, _value{}
-    {
-    }
-
-    bool operator==(const _cpp_value_type& rhs) const
-    {
-      return value() == rhs;
-    }
-
-    bool operator!=(const _cpp_value_type& rhs) const
-    {
-      return not operator==(rhs);
-    }
-
-    void _validate()
-    {
-      _is_valid = true;
-    }
-
-    void _invalidate()
-    {
-      _is_valid = false;
-      _is_null = true;
-      _value = {};
-    }
-
-    bool is_null() const
-    {
-      if (not _is_valid)
-      {
-        throw exception("accessing is_null in non-existing row");
-      }
-      return _is_null;
-    }
-
-    _cpp_value_type value() const
-    {
-      if (not _is_valid)
-      {
-        throw exception("accessing value in non-existing row");
-      }
-
-      if (_is_null)
-      {
-          return {};
-      }
-      return _value;
-    }
-
-    operator _cpp_value_type() const
-    {
-      return value();
-    }
-
-    bool _is_valid;
-    bool _is_null;
-    _cpp_storage_type _value;
-  };
-}  // namespace sqlpp

include/sqlpp11/result_row.h

@@ -28,6 +28,7 @@
 
 #include <map>
 #include <utility>
+#include <sqlpp11/compat/string_view.h>
 #include <sqlpp11/data_types/text.h>
 #include <sqlpp11/detail/index_sequence.h>
 #include <sqlpp11/dynamic_select_column_list.h>
@@ -43,32 +44,22 @@ namespace sqlpp
     struct result_row_impl;
 
     template <typename Db, std::size_t index, typename FieldSpec>
-    struct result_field : public member_t<FieldSpec, result_field_t<Db, FieldSpec>>
+    struct result_field : public member_t<FieldSpec, typename FieldSpec::cpp_type>
     {
-      using _field = member_t<FieldSpec, result_field_t<Db, FieldSpec>>;
+      using _field = member_t<FieldSpec, typename FieldSpec::cpp_type>;
 
       result_field() = default;
 
-      void _validate()
+      template <typename Target>
+      void _bind_field(Target& target)
       {
-        _field::operator()()._validate();
-      }
-
-      void _invalidate()
-      {
-        _field::operator()()._invalidate();
+        target.bind_field(index, _field::operator()());
       }
 
       template <typename Target>
-      void _bind(Target& target)
+      void _read_field(Target& target)
       {
-        _field::operator()()._bind(target, index);
-      }
-
-      template <typename Target>
-      void _post_bind(Target& target)
-      {
-        _field::operator()()._post_bind(target, index);
+        target.read_field(index, _field::operator()());
       }
 
       template <typename Callable>
@@ -90,30 +81,18 @@ namespace sqlpp
     {
       result_row_impl() = default;
 
-      void _validate()
+      template <typename Target>
+      void _bind_fields(Target& target)
       {
         using swallow = int[];
-        (void)swallow{(result_field<Db, Is, FieldSpecs>::_validate(), 0)...};
-      }
-
-      void _invalidate()
-      {
-        using swallow = int[];
-        (void)swallow{(result_field<Db, Is, FieldSpecs>::_invalidate(), 0)...};
+        (void)swallow{(result_field<Db, Is, FieldSpecs>::_bind_field(target), 0)...};
       }
 
       template <typename Target>
-      void _bind(Target& target)
+      void _read_fields(Target& target)
       {
         using swallow = int[];
-        (void)swallow{(result_field<Db, Is, FieldSpecs>::_bind(target), 0)...};
-      }
-
-      template <typename Target>
-      void _post_bind(Target& target)
-      {
-        using swallow = int[];
-        (void)swallow{(result_field<Db, Is, FieldSpecs>::_post_bind(target), 0)...};
+        (void)swallow{(result_field<Db, Is, FieldSpecs>::_read_field(target), 0)...};
       }
 
       template <typename Callable>
@@ -154,13 +133,11 @@ namespace sqlpp
 
     void _validate()
     {
-      _impl::_validate();
       _is_valid = true;
     }
 
     void _invalidate()
     {
-      _impl::_invalidate();
       _is_valid = false;
     }
 
@@ -180,15 +157,15 @@ namespace sqlpp
     }
 
     template <typename Target>
-    void _bind(Target& target)
+    void _bind_fields(Target& target)
     {
-      _impl::_bind(target);
+      _impl::_bind_fields(target);
     }
 
     template <typename Target>
-    void _post_bind(Target& target)
+    void _read_fields(Target& target)
     {
-      _impl::_post_bind(target);
+      _impl::_read_fields(target);
     }
 
     template <typename Callable>
@@ -223,7 +200,7 @@ namespace sqlpp
       : public detail::result_row_impl<Db, detail::make_index_sequence<sizeof...(FieldSpecs)>, FieldSpecs...>
   {
     using _impl = detail::result_row_impl<Db, detail::make_index_sequence<sizeof...(FieldSpecs)>, FieldSpecs...>;
-    using _field_type = result_field_t<Db, field_spec_t<no_name_t, text, true>>;
+    using _field_type = sqlpp::string_view;
 
     bool _is_valid{false};
     std::vector<std::string> _dynamic_field_names;
@@ -249,22 +226,12 @@ namespace sqlpp
 
     void _validate()
     {
-      _impl::_validate();
       _is_valid = true;
-      for (auto& field : _dynamic_fields)
-      {
-        field.second._validate();
-      }
     }
 
     void _invalidate()
     {
-      _impl::_invalidate();
       _is_valid = false;
-      for (auto& field : _dynamic_fields)
-      {
-        field.second._invalidate();
-      }
     }
 
     bool operator==(const dynamic_result_row_t& rhs) const
@@ -290,7 +257,7 @@ namespace sqlpp
       std::size_t index = sizeof...(FieldSpecs);
       for (const auto& field_name : _dynamic_field_names)
       {
-        _dynamic_fields.at(field_name)._bind(target, index);
+        target.read_field(index, _dynamic_fields.at(field_name));
         ++index;
       }
     }
@@ -303,7 +270,7 @@ namespace sqlpp
       std::size_t index = sizeof...(FieldSpecs);
       for (const auto& field_name : _dynamic_field_names)
       {
-        _dynamic_fields.at(field_name)._post_bind(target, index);
+        target.post_read(index, _dynamic_fields.at(field_name));
         ++index;
       }
     }
@@ -313,11 +280,9 @@ namespace sqlpp
     {
       _impl::_apply(callable);
 
-      std::size_t index = sizeof...(FieldSpecs);
       for (const auto& field_name : _dynamic_field_names)
       {
-        _dynamic_fields.at(field_name)._apply(callable);
-        ++index;
+        callable(_dynamic_fields.at(field_name));
       }
     }
 
@@ -326,11 +291,9 @@ namespace sqlpp
     {
       _impl::_apply(callable);
 
-      std::size_t index = sizeof...(FieldSpecs);
       for (const auto& field_name : _dynamic_field_names)
       {
-        _dynamic_fields.at(field_name)._apply(callable);
-        ++index;
+        callable(_dynamic_fields.at(field_name));
       }
     }
   };

include/sqlpp11/sqlite3/bind_result.h

@@ -31,6 +31,9 @@
 #include <sqlpp11/exception.h>
 #include <sqlpp11/sqlite3/detail/prepared_statement_handle.h>
 #include <sqlpp11/sqlite3/export.h>
+#include <sqlpp11/compat/optional.h>
+#include <sqlpp11/compat/string_view.h>
+#include <sqlpp11/compat/span.h>
 
 #include <iostream>
 #include <memory>
@@ -83,7 +86,7 @@ namespace sqlpp
           {
             result_row._validate();
           }
-          result_row._bind(*this);
+          result_row._read_fields(*this);
         }
         else
         {
@@ -92,118 +95,119 @@ namespace sqlpp
         }
       }
 
-      void _bind_boolean_result(size_t index, signed char* value, bool* is_null)
+      void read_field(size_t index, bool& value)
       {
         if (_handle->debug)
-          std::cerr << "Sqlite3 debug: binding boolean result " << *value << " at index: " << index << std::endl;
+          std::cerr << "Sqlite3 debug: binding boolean result at index: " << index << std::endl;
 
-        *value = static_cast<signed char>(sqlite3_column_int(_handle->sqlite_statement, static_cast<int>(index)));
-        *is_null = sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)) == SQLITE_NULL;
+        value = static_cast<signed char>(sqlite3_column_int(_handle->sqlite_statement, static_cast<int>(index)));
       }
 
-      void _bind_floating_point_result(size_t index, double* value, bool* is_null)
+      void read_field(size_t index, double& value)
       {
         if (_handle->debug)
-          std::cerr << "Sqlite3 debug: binding floating_point result " << *value << " at index: " << index << std::endl;
+          std::cerr << "Sqlite3 debug: binding floating_point result at index: " << index << std::endl;
 
         switch (sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)))
         {
           case (SQLITE3_TEXT):
-            *value = atof(
+            value = atof(
                 reinterpret_cast<const char*>(sqlite3_column_text(_handle->sqlite_statement, static_cast<int>(index))));
             break;
           default:
-            *value = sqlite3_column_double(_handle->sqlite_statement, static_cast<int>(index));
+            value = sqlite3_column_double(_handle->sqlite_statement, static_cast<int>(index));
         }
-        *is_null = sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)) == SQLITE_NULL;
       }
 
-      void _bind_integral_result(size_t index, int64_t* value, bool* is_null)
+      void read_field(size_t index, int64_t& value)
       {
         if (_handle->debug)
-          std::cerr << "Sqlite3 debug: binding integral result " << *value << " at index: " << index << std::endl;
+          std::cerr << "Sqlite3 debug: reading integral result at index: " << index << std::endl;
 
-        *value = sqlite3_column_int64(_handle->sqlite_statement, static_cast<int>(index));
-        *is_null = sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)) == SQLITE_NULL;
+        value = sqlite3_column_int64(_handle->sqlite_statement, static_cast<int>(index));
       }
 
-      void _bind_unsigned_integral_result(size_t index, uint64_t* value, bool* is_null)
+      void read_field(size_t index, uint64_t& value)
       {
         if (_handle->debug)
-          std::cerr << "Sqlite3 debug: binding unsigned integral result " << *value << " at index: " << index
-                    << std::endl;
+          std::cerr << "Sqlite3 debug: binding unsigned integral result at index: " << index << std::endl;
 
-        *value = static_cast<uint64_t>(sqlite3_column_int64(_handle->sqlite_statement, static_cast<int>(index)));
-        *is_null = sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)) == SQLITE_NULL;
+        value = static_cast<uint64_t>(sqlite3_column_int64(_handle->sqlite_statement, static_cast<int>(index)));
       }
 
-      void _bind_text_result(size_t index, const char** value, size_t* len)
+      void read_field(size_t index, sqlpp::string_view& value)
       {
         if (_handle->debug)
           std::cerr << "Sqlite3 debug: binding text result at index: " << index << std::endl;
 
-        *value =
-            (reinterpret_cast<const char*>(sqlite3_column_text(_handle->sqlite_statement, static_cast<int>(index))));
-        *len = static_cast<size_t>(sqlite3_column_bytes(_handle->sqlite_statement, static_cast<int>(index)));
+        value = sqlpp::string_view(
+            reinterpret_cast<const char*>(sqlite3_column_text(_handle->sqlite_statement, static_cast<int>(index))),
+            static_cast<size_t>(sqlite3_column_bytes(_handle->sqlite_statement, static_cast<int>(index))));
       }
 
-      void _bind_blob_result(size_t index, const uint8_t** value, size_t* len)
+      void read_field(size_t index, sqlpp::span<uint8_t>& value)
       {
         if (_handle->debug)
-          std::cerr << "Sqlite3 debug: binding text result at index: " << index << std::endl;
+          std::cerr << "Sqlite3 debug: binding blob result at index: " << index << std::endl;
 
-        *value =
-            (reinterpret_cast<const uint8_t*>(sqlite3_column_blob(_handle->sqlite_statement, static_cast<int>(index))));
-        *len = static_cast<size_t>(sqlite3_column_bytes(_handle->sqlite_statement, static_cast<int>(index)));
+        value = sqlpp::span<uint8_t>(
+            reinterpret_cast<const uint8_t*>(sqlite3_column_blob(_handle->sqlite_statement, static_cast<int>(index))),
+            static_cast<size_t>(sqlite3_column_bytes(_handle->sqlite_statement, static_cast<int>(index))));
       }
 
-      void _bind_date_result(size_t index, ::sqlpp::chrono::day_point* value, bool* is_null)
+      void read_field(size_t index, ::sqlpp::chrono::day_point& value)
       {
         if (_handle->debug)
           std::cerr << "Sqlite3 debug: binding date result at index: " << index << std::endl;
 
-        *value = {};
-        *is_null = sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)) == SQLITE_NULL;
-        if (*is_null)
-        {
-          return;
-        }
-
         const auto date_string =
             reinterpret_cast<const char*>(sqlite3_column_text(_handle->sqlite_statement, static_cast<int>(index)));
         if (_handle->debug)
           std::cerr << "Sqlite3 debug: date string: " << date_string << std::endl;
-        if (::sqlpp::detail::parse_date(*value, date_string) == false)
+        if (::sqlpp::detail::parse_date(value, date_string) == false)
         {
+          value = {};
           if (_handle->debug)
             std::cerr << "Sqlite3 debug: invalid date result: " << date_string << std::endl;
         }
       }
 
-      void _bind_date_time_result(size_t index, ::sqlpp::chrono::microsecond_point* value, bool* is_null)
+      void read_field(size_t index, ::sqlpp::chrono::microsecond_point& value)
       {
         if (_handle->debug)
           std::cerr << "Sqlite3 debug: binding date result at index: " << index << std::endl;
 
-        *value = {};
-        *is_null = sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)) == SQLITE_NULL;
-        if (*is_null)
-        {
-          return;
-        }
-
         const auto date_time_string =
             reinterpret_cast<const char*>(sqlite3_column_text(_handle->sqlite_statement, static_cast<int>(index)));
         if (_handle->debug)
           std::cerr << "Sqlite3 debug: date_time string: " << date_time_string << std::endl;
         // We treat DATETIME fields as containing either date+time or just date.
-        if (::sqlpp::detail::parse_date_or_timestamp(*value, date_time_string) == false)
+        if (::sqlpp::detail::parse_date_or_timestamp(value, date_time_string) == false)
         {
+        value = {};
           if (_handle->debug)
             std::cerr << "Sqlite3 debug: invalid date_time result: " << date_time_string << std::endl;
         }
       }
 
+      template <typename T>
+      auto read_field(size_t index, sqlpp::optional<T>& value) -> void
+      {
+        const bool is_null = sqlite3_column_type(_handle->sqlite_statement, static_cast<int>(index)) == SQLITE_NULL;
+        if (is_null)
+        {
+          value.reset();
+        }
+        else
+        {
+          if (not value)
+          {
+            value = T{};
+          }
+          read_field(index, *value);
+        }
+      }
+
     private:
       bool next_impl()
       {

tests/core/serialize/Insert.cpp

@@ -47,12 +47,11 @@ int Insert(int, char* [])
           "INSERT INTO tab_bar (beta,gamma) VALUES('cheesecake'," + getTrue() + ")");
   compare(__LINE__, insert_into(bar).set(bar.beta = ::sqlpp::null, bar.gamma = true),
           "INSERT INTO tab_bar (beta,gamma) VALUES(NULL," + getTrue() + ")");
-#if __cplusplus >= 201703L
-  // string_view argument
-  std::string_view cheeseCake = "cheesecake";
-  compare(__LINE__, insert_into(bar).set(bar.beta = cheeseCake, bar.gamma = true),
+  sqlpp::string_view cheeseCake = "cheesecake";
+  compare(__LINE__, insert_into(bar).set(bar.beta = std::string(cheeseCake), bar.gamma = true),
+          "INSERT INTO tab_bar (beta,gamma) VALUES('cheesecake'," + getTrue() + ")");
+  compare(__LINE__, insert_into(bar).set(bar.beta = sqlpp::string_view(cheeseCake), bar.gamma = true),
           "INSERT INTO tab_bar (beta,gamma) VALUES('cheesecake'," + getTrue() + ")");
-#endif
 
   return 0;
 }

tests/core/serialize/Where.cpp

@@ -68,11 +68,12 @@ int Where(int, char*[])
   compare(__LINE__, where(is_equal_to_or_null(bar.beta, ::sqlpp::value_or_null("SQL"))), " WHERE (tab_bar.beta='SQL')");
   compare(__LINE__, where(is_equal_to_or_null(bar.beta, ::sqlpp::value_or_null<sqlpp::text>(::sqlpp::null))),
           " WHERE tab_bar.beta IS NULL");
-#if __cplusplus >= 201703L
+
+  // string argument
+  compare(__LINE__, where(bar.beta == std::string("SQL")), " WHERE (tab_bar.beta='SQL')");
+
   // string_view argument
-  std::string_view sqlString = "SQL";
-  compare(__LINE__, where(bar.beta == sqlString), " WHERE (tab_bar.beta='SQL')");
-#endif
+  compare(__LINE__, where(bar.beta == sqlpp::string_view("SQL")), " WHERE (tab_bar.beta='SQL')");
 
   return 0;
 }

tests/core/types/result_row.cpp

@@ -27,6 +27,8 @@
 #include "Sample.h"
 #include <sqlpp11/sqlpp11.h>
 
+#include "../../include/test_helpers.h"
+
 namespace
 {
   constexpr auto bar = test::TabBar{};
@@ -47,9 +49,9 @@ namespace
       // result fields are as nullable as the expressions they represent
       const auto rows = db(select(bar.alpha, bar.gamma, seven).from(bar).unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "");
+      static_assert(is_optional<decltype(x.alpha)>::value, "");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "");
+      static_assert(not is_optional<decltype(x.s)>::value, "");
     }
   }
 
@@ -61,20 +63,20 @@ namespace
                              .from(foo.join(bar).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value, "left side of (inner) join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "right side of (inner) join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.delta)>::value, "left side of (inner) join cannot be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "right side of (inner) join cannot be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
     {
 	  const auto& rows = db(select(bar.alpha, foo.delta, bar.gamma, seven)
                              .from(bar.join(foo).on(foo.omega > bar.alpha))
                              .unconditionally());
           auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "left side of (inner) join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value, "right side of (inner) join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "left side of (inner) join cannot be null");
+      static_assert(not is_optional<decltype(x.delta)>::value, "right side of (inner) join cannot be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
     {
       MockSizeDb db2;
@@ -91,20 +93,20 @@ namespace
                              .from(foo.inner_join(bar).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value, "left side of inner join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "right side of inner join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.delta)>::value, "left side of inner join cannot be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "right side of inner join cannot be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
     {
       const auto rows = db(select(bar.alpha, foo.delta, bar.gamma, seven)
                              .from(bar.inner_join(foo).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "left side of inner join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value, "right side of inner join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "left side of inner join cannot be null");
+      static_assert(not is_optional<decltype(x.delta)>::value, "right side of inner join cannot be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
 
     // Left outer join
@@ -113,20 +115,20 @@ namespace
                              .from(foo.left_outer_join(bar).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value, "left side of left outer join cannot be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.gamma)>::value, "right side of left outer join can be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.delta)>::value, "left side of left outer join cannot be null");
+      static_assert(is_optional<decltype(x.gamma)>::value, "right side of left outer join can be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
     {
       const auto rows = db(select(bar.alpha, foo.delta, bar.gamma, seven)
                              .from(bar.left_outer_join(foo).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "left side of left outer join cannot be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.delta)>::value, "right side of left outer join can be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "left side of left outer join cannot be null");
+      static_assert(is_optional<decltype(x.delta)>::value, "right side of left outer join can be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
 
     // Right outer join
@@ -135,22 +137,22 @@ namespace
                              .from(foo.right_outer_join(bar).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.delta)>::value, "left side of right outer join can be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value,
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(is_optional<decltype(x.delta)>::value, "left side of right outer join can be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value,
                     "right side of right outer join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
     {
       const auto rows = db(select(bar.alpha, foo.delta, bar.gamma, seven)
                              .from(bar.right_outer_join(foo).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.gamma)>::value, "left side of right outer join can be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value,
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(is_optional<decltype(x.gamma)>::value, "left side of right outer join can be null");
+      static_assert(not is_optional<decltype(x.delta)>::value,
                     "right side of right outer join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
 
     // Outer join
@@ -159,20 +161,20 @@ namespace
                              .from(foo.outer_join(bar).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.delta)>::value, "left side of outer join can be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.gamma)>::value, "right side of outer join can be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(is_optional<decltype(x.delta)>::value, "left side of outer join can be null");
+      static_assert(is_optional<decltype(x.gamma)>::value, "right side of outer join can be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
     {
       const auto rows = db(select(bar.alpha, foo.delta, bar.gamma, seven)
                              .from(bar.outer_join(foo).on(foo.omega > bar.alpha))
                              .unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.gamma)>::value, "left side of outer join can be null");
-      static_assert(sqlpp::can_be_null_t<decltype(x.delta)>::value, "right side of outer join can be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(is_optional<decltype(x.gamma)>::value, "left side of outer join can be null");
+      static_assert(is_optional<decltype(x.delta)>::value, "right side of outer join can be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
 
     // Cross join
@@ -180,19 +182,19 @@ namespace
       const auto rows =
           db(select(bar.alpha, foo.delta, bar.gamma, seven).from(foo.cross_join(bar)).unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value, "left side of cross join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "right side of cross join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.delta)>::value, "left side of cross join cannot be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "right side of cross join cannot be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
     {
       const auto rows =
           db(select(bar.alpha, foo.delta, bar.gamma, seven).from(bar.cross_join(foo)).unconditionally());
       auto& x = rows.front();
-      static_assert(sqlpp::can_be_null_t<decltype(x.alpha)>::value, "nullable value can always be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.gamma)>::value, "left side of cross join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.delta)>::value, "right side of cross join cannot be null");
-      static_assert(not sqlpp::can_be_null_t<decltype(x.s)>::value, "constant non-null value can not be null");
+      static_assert(is_optional<decltype(x.alpha)>::value, "nullable value can always be null");
+      static_assert(not is_optional<decltype(x.gamma)>::value, "left side of cross join cannot be null");
+      static_assert(not is_optional<decltype(x.delta)>::value, "right side of cross join cannot be null");
+      static_assert(not is_optional<decltype(x.s)>::value, "constant non-null value can not be null");
     }
   }
 
@@ -205,11 +207,11 @@ namespace
       static_assert(sqlpp::can_be_null_t<decltype(a)>::value, "");
       const auto rows = db(select(count(a), avg(a), max(a), min(a), sum(a)).from(bar).unconditionally());
       auto& x = rows.front();
-      static_assert(not sqlpp::can_be_null_t<decltype(x.count)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.avg)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.sum)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.max)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.min)>::value, "");
+      static_assert(not is_optional<decltype(x.count)>::value, "");
+      static_assert(is_optional<decltype(x.avg)>::value, "");
+      static_assert(is_optional<decltype(x.sum)>::value, "");
+      static_assert(is_optional<decltype(x.max)>::value, "");
+      static_assert(is_optional<decltype(x.min)>::value, "");
     }
     {
       // aggregates of nullable values
@@ -218,11 +220,11 @@ namespace
       static_assert(sqlpp::can_be_null_t<decltype(o)>::value, "");
       const auto rows = db(select(count(o), avg(o), max(o), min(o), sum(o)).from(foo).unconditionally());
       auto& x = rows.front();
-      static_assert(not sqlpp::can_be_null_t<decltype(x.count)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.avg)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.sum)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.max)>::value, "");
-      static_assert(sqlpp::can_be_null_t<decltype(x.min)>::value, "");
+      static_assert(not is_optional<decltype(x.count)>::value, "");
+      static_assert(is_optional<decltype(x.avg)>::value, "");
+      static_assert(is_optional<decltype(x.sum)>::value, "");
+      static_assert(is_optional<decltype(x.max)>::value, "");
+      static_assert(is_optional<decltype(x.min)>::value, "");
     }
   }
 }

tests/core/usage/CustomQuery.cpp

@@ -28,6 +28,7 @@
 #include "MockDb.h"
 #include <sqlpp11/sqlpp11.h>
 #include <sqlpp11/custom_query.h>
+#include "../../include/test_helpers.h"
 
 namespace
 {

tests/core/usage/DateTime.cpp

@@ -28,6 +28,8 @@
 #include "MockDb.h"
 #include <sqlpp11/sqlpp11.h>
 
+#include "../../include/test_helpers.h"
+
 SQLPP_ALIAS_PROVIDER(now)
 
 #if _MSC_FULL_VER >= 190023918

tests/core/usage/Insert.cpp

@@ -27,9 +27,7 @@
 #include "Sample.h"
 #include "is_regular.h"
 #include <iostream>
-#if __cplusplus >= 201703L
-#include <string_view>
-#endif
+#include <sqlpp11/compat/string_view.h>
 #include <sqlpp11/functions.h>
 #include <sqlpp11/insert.h>
 #include <sqlpp11/select.h>
@@ -109,14 +107,11 @@ int Insert(int, char*[])
   prepared_insert.params.delta = sqlpp::value_or_null(17);
   db(prepared_insert);
 
-#if __cplusplus >= 201703L
   auto prepared_insert_sv = db.prepare(insert_into(t).set(t.gamma = parameter(t.gamma), t.delta = parameter(t.delta), t.beta = parameter(t.beta)));
   prepared_insert_sv.params.gamma = true;
   prepared_insert_sv.params.delta = 17;
-  std::string_view sv = "string_view";
-  prepared_insert_sv.params.beta = sv;
+  prepared_insert_sv.params.beta = sqlpp::string_view("string_view");;
   db(prepared_insert_sv);
-#endif
 
   return 0;
 }

tests/core/usage/Interpret.cpp

@@ -27,7 +27,7 @@
 #include "Sample.h"
 #include <sqlpp11/sqlpp11.h>
 
-#include <iostream>
+#include "../../include/test_helpers.h"
 
 int Interpret(int, char* [])
 {
@@ -171,9 +171,9 @@ int Interpret(int, char* [])
 
   for (const auto& row : db(select(all_of(t)).from(t).unconditionally()))
   {
-    serialize(row.alpha, printer);
-    serialize(row.beta, printer);
-    serialize(row.gamma, printer);
+    serialize(t.alpha == row.alpha.value(), printer);
+    serialize(t.beta == row.beta.value(), printer);
+    serialize(t.gamma == row.gamma, printer);
   }
 
   get_sql_name(t);

tests/core/usage/Prepared.cpp

@@ -28,6 +28,7 @@
 #include "is_regular.h"
 #include <sqlpp11/functions.h>
 #include <sqlpp11/select.h>
+#include "../../include/test_helpers.h"
 
 int Prepared(int, char* [])
 {
@@ -132,7 +133,10 @@ int Prepared(int, char* [])
   // Can we prepare a query without parameters?
   {
     auto ps = db.prepare(select(all_of(t)).from(t).where((t.beta.like("%"))));
-    auto res = db(ps);
+    for (const auto& row : db(ps))
+    {
+      std::cerr << row.alpha << std::endl;
+    }
   }
 
   // Check that a prepared select is default-constructable

tests/core/usage/Result.cpp

@@ -28,6 +28,9 @@
 #include "MockDb.h"
 #include <sqlpp11/sqlpp11.h>
 
+
+#include "../../include/test_helpers.h"
+
 int Result(int, char* [])
 {
   MockDb db = {};
@@ -39,28 +42,24 @@ int Result(int, char* [])
   // Using a non-enforcing db
   for (const auto& row : db(select(all_of(t), t.beta.like("")).from(t).unconditionally()))
   {
-    static_assert(sqlpp::can_be_null_t<decltype(row.alpha)>::value, "row.alpha can be null");
-    static_assert(std::is_same<bool, decltype(row.alpha.is_null())>::value, "Yikes");
-    using T = sqlpp::wrap_operand_t<decltype(row.alpha)>;
-    static_assert(sqlpp::can_be_null_t<T>::value, "row.alpha can be null");
-    static_assert(sqlpp::is_result_field_t<T>::value, "result_fields are not wrapped");
+    static_assert(is_optional<decltype(row.alpha)>::value, "row.alpha can be null");
 
-    for (const auto& sub : db(select(all_of(t)).from(t).where(t.alpha == row.alpha)))
+    for (const auto& sub : db(select(all_of(t)).from(t).where(t.alpha == row.alpha.value())))
     {
       std::cerr << sub.alpha << std::endl;
     }
-    db(insert_into(t).set(t.beta = row.beta, t.gamma = false));
+    db(insert_into(t).set(t.beta = row.beta.value(), t.gamma = false));
   }
 
   sqlpp::select((t.alpha + 1).as(t.alpha)).flags(sqlpp::all).from(t);
   for (const auto& row : db(select(all_of(t)).from(t).unconditionally()))
   {
-    static_assert(sqlpp::can_be_null_t<decltype(row.alpha)>::value, "row.alpha can be null");
+    static_assert(is_optional<decltype(row.alpha)>::value, "row.alpha can be null");
   }
 
   for (const auto& row : db(select(all_of(t)).from(t).unconditionally()))
   {
-    static_assert(sqlpp::can_be_null_t<decltype(row.alpha)>::value, "row.alpha can be null");
+    static_assert(is_optional<decltype(row.alpha)>::value, "row.alpha can be null");
   }
 
   sqlpp::select((t.alpha + 1).as(t.alpha)).flags(sqlpp::all).from(t);

tests/core/usage/Select.cpp

@@ -33,13 +33,14 @@
 #include <sqlpp11/functions.h>
 #include <sqlpp11/select.h>
 #include <sqlpp11/without_table_check.h>
+#include "../../include/test_helpers.h"
 
 template <typename Db, typename Column>
 int64_t getColumn(Db&& db, const Column& column)
 {
   auto result = db(select(column.as(sqlpp::alias::a)).from(column.table()).unconditionally());
-  if (not result.empty())
-    return result.front().a;
+  if (not result.empty() and result.front().a.has_value())
+    return result.front().a.value();
   else
     return 0;
 }
@@ -49,15 +50,15 @@ struct to_cerr
   template <typename Field>
   auto operator()(const Field& field) const -> void
   {
-    std::cerr << get_sql_name(field) << " = " << field << std::endl;
+    std::cerr << field << std::endl;
   }
 };
 
 template <typename Row>
 void print_row(Row const& row)
 {
-  int64_t a = row.alpha;
-  const std::string b = row.beta;
+  const sqlpp::optional<int64_t> a = row.alpha;
+  const sqlpp::optional<sqlpp::string_view> b = row.beta;
   std::cout << a << ", " << b << std::endl;
 }
 
@@ -90,16 +91,16 @@ int Select(int, char*[])
 
   for (const auto& row : db(select(all_of(t)).from(t).unconditionally()))
   {
-    int64_t a = row.alpha;
-    const std::string b = row.beta;
+    const sqlpp::optional<int64_t> a = row.alpha;
+    const sqlpp::optional<sqlpp::string_view> b = row.beta;
     std::cout << a << ", " << b << std::endl;
   }
 
   for (const auto& row :
        db(select(all_of(t), t.gamma.as(t)).from(t).where(t.alpha > 7 and trim(t.beta) == "test").for_update()))
   {
-    int64_t a = row.alpha;
-    const std::string b = row.beta;
+    const sqlpp::optional<int64_t> a = row.alpha;
+    const sqlpp::optional<sqlpp::string_view> b = row.beta;
     const bool g = row.tabBar;
     std::cout << a << ", " << b << ", " << g << std::endl;
   }
@@ -177,7 +178,7 @@ int Select(int, char*[])
   s.order_by.add(t.delta.order(sqlpp::sort_type::desc));
   for (const auto& row : db(db.prepare(s)))
   {
-    int64_t a = row.alpha;
+    const sqlpp::optional<int64_t> a = row.alpha;
     std::cout << a << std::endl;
   }
 
@@ -187,7 +188,7 @@ int Select(int, char*[])
   select(sqlpp::value(7).as(t.alpha));
 
   for (const auto& row :
-       db(select(sqlpp::case_when(true).then(sqlpp::null).else_(sqlpp::null).as(t.beta)).from(t).unconditionally()))
+       db(select(sqlpp::case_when(true).then(t.beta).else_(sqlpp::null).as(t.beta)).from(t).unconditionally()))
   {
     std::cerr << row.beta << std::endl;
   }

tests/core/usage/SelectType.cpp

@@ -32,6 +32,7 @@
 #include <sqlpp11/functions.h>
 #include <sqlpp11/select.h>
 #include <sqlpp11/without_table_check.h>
+#include "../../include/test_helpers.h"
 
 namespace alias
 {
@@ -345,7 +346,7 @@ int SelectType(int, char*[])
 
   for (const auto& row : db(select(all_of(t)).from(t).unconditionally()))
   {
-    int64_t a = row.alpha;
+    const auto a = row.alpha;
     std::cout << a << std::endl;
   }
 

tests/core/usage/With.cpp

@@ -28,6 +28,7 @@
 #include <sqlpp11/select.h>
 #include <sqlpp11/alias_provider.h>
 #include <iostream>
+#include "../../include/test_helpers.h"
 
 int With(int, char*[])
 {

tests/include/test_helpers.h

@@ -0,0 +1,104 @@
+#pragma once
+
+/*
+ * Copyright (c) 2024, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <iostream>
+#include <sqlpp11/sqlpp11.h>
+
+template <typename Clock, typename Period>
+std::ostream& operator<<(std::ostream& os, const std::chrono::time_point<Clock, Period>& t)
+{
+  const auto dp = ::sqlpp::chrono::floor<::date::days>(t);
+  const auto ymd = ::date::year_month_day{dp};
+  const auto time = ::date::make_time(t - dp);
+  os << "TIMESTAMP '" << ymd << ' ' << time << "'";
+  return os;
+}
+
+template <typename Rep, typename Period>
+std::ostream& operator<<(std::ostream& os, const std::chrono::duration<Rep, Period>& t)
+{
+  return os << '\'' << ::date::make_time(t) << '\'';
+}
+
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const sqlpp::optional<T>& t)
+{
+  if (not t)
+    return os << "NULL";
+  return os << t.value();
+}
+
+inline std::ostream& operator<<(std::ostream& stream, const sqlpp::isolation_level& level)
+{
+  switch (level)
+  {
+    case sqlpp::isolation_level::serializable:
+    {
+      stream << "SERIALIZABLE";
+      break;
+    }
+    case sqlpp::isolation_level::repeatable_read:
+    {
+      stream << "REPEATABLE READ";
+      break;
+    }
+    case sqlpp::isolation_level::read_committed:
+    {
+      stream << "READ COMMITTED";
+      break;
+    }
+    case sqlpp::isolation_level::read_uncommitted:
+    {
+      stream << "READ UNCOMMITTED";
+      break;
+    }
+    case sqlpp::isolation_level::undefined:
+    {
+      stream << "BEGIN";
+      break;
+    }
+  }
+
+  return stream;
+}
+
+template <typename L, typename R>
+auto require_equal(int line, const L& l, const R& r) -> void
+{
+  if (l != r)
+  {
+    std::cerr << line << ": " << l << " != " << r << std::endl;
+    throw std::runtime_error("Unexpected result");
+  }
+}
+
+template <typename T>
+struct is_optional : public std::false_type{};
+
+template <typename T>
+struct is_optional<sqlpp::optional<T>> : public std::true_type{};
+

tests/mysql/usage/DateTime.cpp

@@ -28,6 +28,8 @@
 #include <sqlpp11/mysql/mysql.h>
 #include <sqlpp11/sqlpp11.h>
 
+#include "../../include/test_helpers.h"
+
 #include <cassert>
 #include <iostream>
 #include <vector>
@@ -36,20 +38,6 @@ const auto library_raii = sqlpp::mysql::scoped_library_initializer_t{};
 
 namespace
 {
-  template <typename L, typename R>
-  auto require_equal(int line, const L& l, const R& r) -> void
-  {
-    if (l != r)
-    {
-      std::cerr << line << ": ";
-      serialize(::sqlpp::wrap_operand_t<L>{l}, std::cerr);
-      std::cerr << " != ";
-      serialize(::sqlpp::wrap_operand_t<R>{r}, std::cerr);
-      std::cerr << "\n" ;
-      throw std::runtime_error("Unexpected result");
-    }
-  }
-
   template <typename L, typename R>
   auto require_close(int line, const L& l, const R& r) -> void
   {
@@ -90,13 +78,10 @@ int DateTime(int, char*[])
     db(insert_into(tab).default_values());
     for (const auto& row : db(select(all_of(tab)).from(tab).unconditionally()))
     {
-      require_equal(__LINE__, row.colDayPoint.is_null(), true);
-      require_equal(__LINE__, row.colDayPoint.value(), ::sqlpp::chrono::day_point{});
-      require_equal(__LINE__, row.colTimePoint.is_null(), true);
-      require_equal(__LINE__, row.colTimePoint.value(), ::sqlpp::chrono::microsecond_point{});
-      require_close(__LINE__, row.colDateTimePoint.value(), now);
-      require_equal(__LINE__, row.colTimeOfDay.is_null(), true);
-      require_equal(__LINE__, row.colTimeOfDay.value(), ::std::chrono::microseconds{});
+      require_equal(__LINE__, row.colDayPoint.has_value(), false);
+      require_equal(__LINE__, row.colTimePoint.has_value(), false);
+      require_close(__LINE__, row.colDateTimePoint, now);
+      require_equal(__LINE__, row.colTimeOfDay.has_value(), false);
     }
 
     db(update(tab).set(tab.colDayPoint = today, tab.colTimePoint = now, tab.colTimeOfDay = current).unconditionally());
@@ -111,8 +96,7 @@ int DateTime(int, char*[])
     auto statement = db.prepare(select(all_of(tab)).from(tab).unconditionally());
     for (const auto& row : db(statement))
     {
-      require_equal(__LINE__, row.colDateTimePoint.is_null(), false);
-      require_close(__LINE__, row.colDateTimePoint.value(), now);
+      require_close(__LINE__, row.colDateTimePoint, now);
       require_equal(__LINE__, row.colDayPoint.value(), today);
       require_equal(__LINE__, row.colTimePoint.value(), now);
       require_close(__LINE__, row.colTimeOfDay.value(), current);

tests/mysql/usage/DynamicSelect.cpp

@@ -48,9 +48,9 @@ int DynamicSelect(int, char*[])
     auto db = sql::make_test_connection();
     db.execute(R"(DROP TABLE IF EXISTS tab_sample)");
     db.execute(R"(CREATE TABLE tab_sample (
-		alpha bigint(20) DEFAULT NULL,
+		alpha bigint(20) AUTO_INCREMENT NOT NULL PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool NOT NULL DEFAULT 0
 			))");
 
     const auto tab = TabSample{};

tests/mysql/usage/Json.cpp

@@ -78,10 +78,10 @@ int Json(int, char*[])
     if (result.empty())
       throw std::runtime_error{"selection result is empty"};
 
-    const std::string value = result.front().value;
+    const sqlpp::optional<sqlpp::string_view> value = result.front().value;
 
     if (value != "value")
-      throw std::runtime_error{std::string{"unexpected value: "} + value};
+      throw std::runtime_error{std::string{"unexpected value: "} + std::string(value ? value.value() : "NULL")};
   }
   catch (const std::exception& e)
   {

tests/mysql/usage/MoveConstructor.cpp

@@ -50,9 +50,9 @@ int MoveConstructor(int, char*[])
 
     connections.at(0).execute(R"(DROP TABLE IF EXISTS tab_sample)");
     connections.at(0).execute(R"(CREATE TABLE tab_sample (
-		alpha bigint(20) DEFAULT NULL,
+		alpha bigint(20) AUTO_INCREMENT NOT NULL PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool NOT NULL DEFAULT 0
 			))");
 
     assert(connections.at(0).is_transaction_active() == false);

tests/mysql/usage/Sample.cpp

@@ -27,6 +27,7 @@
 #include "TabSample.h"
 #include <sqlpp11/mysql/mysql.h>
 #include <sqlpp11/sqlpp11.h>
+#include "../../include/test_helpers.h"
 
 #include <cassert>
 #include <iostream>
@@ -82,9 +83,9 @@ int Sample(int, char*[])
     const auto y = db.prepare(x);
     for (const auto& row : db(db.prepare(select(all_of(tab)).from(tab).unconditionally())))
     {
-      std::cerr << "alpha: " << row.alpha.is_null() << std::endl;
-      std::cerr << "beta: " << row.beta.is_null() << std::endl;
-      std::cerr << "gamma: " << row.gamma.is_null() << std::endl;
+      std::cerr << "alpha: " << row.alpha << std::endl;
+      std::cerr << "beta: " << row.beta << std::endl;
+      std::cerr << "gamma: " << row.gamma << std::endl;
     }
     db(insert_into(tab).set(tab.beta = "kaesekuchen", tab.gamma = true));
     db(insert_into(tab).default_values());
@@ -122,8 +123,8 @@ int Sample(int, char*[])
       auto result = db(select(all_of(tab), select(max(tab.alpha)).from(tab)).from(tab).unconditionally());
       if (const auto& row = *result.begin())
       {
-        long a = row.alpha;
-        long m = row.max;
+        const int64_t a = row.alpha;
+        const sqlpp::optional<long> m = row.max;
         std::cerr << __LINE__ << " row.alpha: " << a << ", row.max: " << m << std::endl;
       }
       tx.commit();

tests/mysql/usage/Select.cpp

@@ -34,6 +34,7 @@
 #include <sqlpp11/select.h>
 #include <sqlpp11/transaction.h>
 #include <sqlpp11/update.h>
+#include "../../include/test_helpers.h"
 
 #include <iostream>
 #include <vector>
@@ -91,7 +92,7 @@ int Select(int, char*[])
     db.execute(R"(CREATE TABLE tab_sample (
 		alpha bigint(20) AUTO_INCREMENT,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL,
+			gamma bool NOT NULL DEFAULT 0,
 			PRIMARY KEY (alpha)
 			))");
     db.execute(R"(DROP TABLE IF EXISTS tab_foo)");
@@ -153,8 +154,8 @@ int Select(int, char*[])
       auto result = db(select(all_of(tab), select(max(tab.alpha)).from(tab)).from(tab).unconditionally());
       if (const auto& row = *result.begin())
       {
-        long a = row.alpha;
-        long m = row.max;
+        sqlpp::optional<long> a = row.alpha;
+        sqlpp::optional<long> m = row.max;
         std::cerr << "-----------------------------" << a << ", " << m << std::endl;
       }
       tx.commit();

tests/mysql/usage/Truncated.cpp

@@ -34,6 +34,7 @@
 #include <sqlpp11/select.h>
 #include <sqlpp11/transaction.h>
 #include <sqlpp11/update.h>
+#include "../../include/test_helpers.h"
 
 #include <iostream>
 #include <vector>
@@ -51,14 +52,13 @@ int Truncated(int, char*[])
     auto db = sql::make_test_connection();
     db.execute(R"(DROP TABLE IF EXISTS tab_sample)");
     db.execute(R"(CREATE TABLE tab_sample (
-		alpha bigint(20) AUTO_INCREMENT,
+		alpha bigint(20) AUTO_INCREMENT NOT NULL PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL,
-			PRIMARY KEY (alpha)
+			gamma bool NOT NULL DEFAULT 0
 			))");
     db.execute(R"(DROP TABLE IF EXISTS tab_foo)");
     db.execute(R"(CREATE TABLE tab_foo (
-		omega bigint(20) DEFAULT NULL
+		omega bigint(20) NOT NULL
 			))");
 
     db(insert_into(tab).set(tab.gamma = true, tab.beta = "cheese"));

tests/mysql/usage/Union.cpp

@@ -27,6 +27,7 @@
 #include "TabSample.h"
 #include <sqlpp11/mysql/connection.h>
 #include <sqlpp11/sqlpp11.h>
+#include "../../include/test_helpers.h"
 
 #include <iostream>
 

tests/postgresql/usage/Blob.cpp

@@ -41,35 +41,30 @@ const auto blob = model::BlobSample{};
 constexpr size_t blob_size = 1000 * 1000ul;
 constexpr size_t blob_small_size = 999;
 
-void verify_blob(sql::connection& db, const std::vector<uint8_t>& data, uint64_t id)
+void verify_blob(sql::connection& db, const std::vector<uint8_t>& expected, uint64_t id)
 {
   auto result = db(select(blob.data).from(blob).where(blob.id == id));
   const auto& result_row = result.front();
-  std::cerr << "id: " << id << std::endl;
-  std::cerr << "Insert size: " << data.size() << std::endl;
-  std::cerr << "Select size: " << result_row.data.len << std::endl;
-  if (data.size() != result_row.data.len)
+  if (!result_row.data)
+    throw  std::runtime_error("blob data is unpexpectedly NULL for id " + std::to_string(id));
+  const auto received = *result_row.data;
+
+  if (expected.size() != received.size())
   {
     std::cerr << "Size mismatch" << std::endl;
 
-    throw std::runtime_error("Size mismatch " + std::to_string(data.size()) +
-                             " != " + std::to_string(result_row.data.len));
+    throw std::runtime_error("Size mismatch " + std::to_string(expected.size()) +
+                             " != " + std::to_string(received.size()));
   }
   std::cerr << "Verifying content" << std::endl;
-  const auto result_blob = result_row.data.value();
-  if (data != result_blob)
+  for (size_t i = 0; i < expected.size(); i++)
   {
-    std::cout << "Content mismatch ([row] original -> received)" << std::endl;
-
-    for (size_t i = 0; i < data.size(); i++)
+    if (expected[i] != received[i])
     {
-      if (data[i] != result_row.data.value()[i])
-      {
-        std::cerr << "[" << i << "] " << static_cast<int>(data.at(i)) << " -> " << static_cast<int>(result_blob.at(i))
-                  << std::endl;
-      }
+      std::cerr << "expected[" << i << "] " << static_cast<int>(expected[i]) << " != received " << static_cast<int>(received[i])
+                << std::endl;
+      throw std::runtime_error("Content mismatch");
     }
-    throw std::runtime_error("Content mismatch");
   }
 }
 
@@ -108,12 +103,10 @@ int Blob(int, char*[])
   {
     auto result = db(select(blob.data).from(blob).where(blob.id == null_id));
     const auto& result_row = result.front();
-    std::cerr << "Null blob is_null:\t" << std::boolalpha << result_row.data.is_null() << std::endl;
-    std::cerr << "Null blob len == 0:\t" << std::boolalpha << (result_row.data.len == 0) << std::endl;
-    std::cerr << "Null blob blob == nullptr:\t" << std::boolalpha << (result_row.data.is_null()) << std::endl;
-    if (!result_row.data.is_null() || result_row.data.len != 0)
+    std::cerr << "Null blob is_null:\t" << std::boolalpha << (result_row.data == sqlpp::nullopt) << std::endl;
+    if (result_row.data.has_value())
     {
-      throw std::runtime_error("Null blob has incorrect values");
+      throw std::runtime_error("Expected NULL blob has value");
     }
   }
 

tests/postgresql/usage/Date.cpp

@@ -93,10 +93,8 @@ int Date(int, char*[])
       db(insert_into(tab).default_values());
       for (const auto& row : db(select(all_of(tab)).from(tab).unconditionally()))
       {
-        require_equal(__LINE__, row.colDayPoint.is_null(), true);
-        require_equal(__LINE__, row.colDayPoint.value(), ::sqlpp::chrono::day_point{});
-        require_equal(__LINE__, row.colTimePoint.is_null(), true);
-        require_equal(__LINE__, row.colTimePoint.value(), ::sqlpp::chrono::microsecond_point{});
+        require_equal(__LINE__, row.colDayPoint.has_value(), false);
+        require_equal(__LINE__, row.colTimePoint.has_value(), false);
       }
 
       db(update(tab).set(tab.colDayPoint = today, tab.colTimePoint = now).unconditionally());

tests/postgresql/usage/DateTime.cpp

@@ -75,12 +75,9 @@ int DateTime(int, char*[])
     db(insert_into(tab).default_values());
     for (const auto& row : db(select(all_of(tab)).from(tab).unconditionally()))
     {
-      require_equal(__LINE__, row.c_day.is_null(), true);
-      require_equal(__LINE__, row.c_day.value(), ::sqlpp::chrono::day_point{});
-      require_equal(__LINE__, row.c_time.is_null(), true);
-      require_equal(__LINE__, row.c_time.value(), ::std::chrono::microseconds{});
-      require_equal(__LINE__, row.c_timepoint.is_null(), true);
-      require_equal(__LINE__, row.c_timepoint.value(), ::sqlpp::chrono::microsecond_point{});
+      require_equal(__LINE__, row.c_day.has_value(), false);
+      require_equal(__LINE__, row.c_time.has_value(), false);
+      require_equal(__LINE__, row.c_timepoint.has_value(), false);
     }
 
     db(update(tab).set(tab.c_day = today, tab.c_time = current, tab.c_timepoint = now).unconditionally());

tests/postgresql/usage/InsertOnConflict.cpp

@@ -33,6 +33,7 @@
 #include "TabBar.h"
 #include "TabFoo.h"
 #include "make_test_connection.h"
+#include "../../include/test_helpers.h"
 
 namespace sql = sqlpp::postgresql;
 

tests/postgresql/usage/Returning.cpp

@@ -2,6 +2,7 @@
 
 #include <sqlpp11/postgresql/postgresql.h>
 #include <sqlpp11/sqlpp11.h>
+#include "../../include/test_helpers.h"
 
 #include "TabFoo.h"
 #include "make_test_connection.h"

tests/postgresql/usage/Select.cpp

@@ -32,6 +32,7 @@
 
 #include "TabFoo.h"
 #include "make_test_connection.h"
+#include "../../include/test_helpers.h"
 
 namespace sql = sqlpp::postgresql;
 model::TabFoo tab = {};
@@ -69,7 +70,7 @@ int Select(int, char*[])
   db.execute(R"(DROP TABLE IF EXISTS tabfoo;)");
   db.execute(R"(CREATE TABLE tabfoo
              (
-               alpha bigserial NOT NULL,
+               alpha bigserial,
                beta smallint,
                gamma text,
                c_bool boolean,
@@ -112,8 +113,8 @@ int Select(int, char*[])
   db(insert_into(tab).set(tab.c_bool = false, tab.gamma = "asdfg"));
 
   assert(db(select(tab.c_bool).from(tab).where(tab.gamma == "asdf")).front().c_bool);
-  assert(not db(select(tab.c_bool).from(tab).where(tab.gamma == "asdfg")).front().c_bool);
-  assert(not db(select(tab.c_bool).from(tab).where(tab.alpha == 1)).front().c_bool);
+  assert(not db(select(tab.c_bool).from(tab).where(tab.gamma == "asdfg")).front().c_bool.value());
+  assert(not db(select(tab.c_bool).from(tab).where(tab.alpha == 1)).front().c_bool.has_value());
 
   // test
 

tests/postgresql/usage/Transaction.cpp

@@ -32,56 +32,10 @@
 #include <sqlpp11/postgresql/connection.h>
 #include <sqlpp11/sqlpp11.h>
 #include <sqlpp11/transaction.h>
+#include "../../include/test_helpers.h"
 
 #include "make_test_connection.h"
 
-namespace
-{
-  std::ostream& operator<<(std::ostream& stream, const sqlpp::isolation_level& level)
-  {
-    switch (level)
-    {
-      case sqlpp::isolation_level::serializable:
-      {
-        stream << "SERIALIZABLE";
-        break;
-      }
-      case sqlpp::isolation_level::repeatable_read:
-      {
-        stream << "REPEATABLE READ";
-        break;
-      }
-      case sqlpp::isolation_level::read_committed:
-      {
-        stream << "READ COMMITTED";
-        break;
-      }
-      case sqlpp::isolation_level::read_uncommitted:
-      {
-        stream << "READ UNCOMMITTED";
-        break;
-      }
-      case sqlpp::isolation_level::undefined:
-      {
-        stream << "BEGIN";
-        break;
-      }
-    }
-
-    return stream;
-  }
-
-  template <typename L, typename R>
-  void require_equal(int line, const L& l, const R& r)
-  {
-    if (l != r)
-    {
-      std::cerr << line << ": " << l << " != " << r << std::endl;
-      throw std::runtime_error("Unexpected result");
-    }
-  }
-}
-
 namespace sql = sqlpp::postgresql;
 
 SQLPP_ALIAS_PROVIDER(level);
@@ -95,10 +49,10 @@ int Transaction(int, char*[])
 
     {
       require_equal(__LINE__, db.is_transaction_active(), false);
-      auto current_level = db(custom_query(sqlpp::verbatim("show transaction_isolation;"))
-                                  .with_result_type_of(select(sqlpp::value("").as(level))))
-                               .front()
-                               .level;
+      auto current_level = std::string(db(custom_query(sqlpp::verbatim("show transaction_isolation;"))
+                                              .with_result_type_of(select(sqlpp::value("").as(level))))
+                                           .front()
+                                           .level);
       require_equal(__LINE__, current_level, "read committed");
       std::cerr << "isolation level outside transaction: " << current_level << "\n";
 

tests/postgresql/usage/Type.cpp

@@ -51,7 +51,7 @@ namespace
   {
     // prepare test with timezone
     db.execute("DROP TABLE IF EXISTS tab_sample");
-    db.execute("CREATE TABLE tab_sample (alpha bigint, beta text, gamma bool)");
+    db.execute("CREATE TABLE tab_sample (alpha bigint, beta text, gamma bool NOT NULL DEFAULT 'f')");
   }
 }
 
@@ -69,24 +69,20 @@ int Type(int, char*[])
     db(insert_into(tab).default_values());
     for (const auto& row : db(select(all_of(tab)).from(tab).unconditionally()))
     {
-      require_equal(__LINE__, row.alpha.is_null(), true);
-      require_equal(__LINE__, row.alpha.value(), 0);
-      require_equal(__LINE__, row.beta.is_null(), true);
-      require_equal(__LINE__, row.beta.value(), "");
-      require_equal(__LINE__, row.gamma.is_null(), true);
-      require_equal(__LINE__, row.gamma.value(), false);
+      require_equal(__LINE__, row.alpha.has_value(), false);
+      require_equal(__LINE__, row.beta.has_value(), false);
+      require_equal(__LINE__, row.gamma, false);
     }
 
     db(update(tab).set(tab.alpha = 10, tab.beta = "Cookies!", tab.gamma = true).unconditionally());
 
     for (const auto& row : db(select(all_of(tab)).from(tab).unconditionally()))
     {
-      require_equal(__LINE__, row.alpha.is_null(), false);
+      require_equal(__LINE__, row.alpha.has_value(), true);
       require_equal(__LINE__, row.alpha.value(), 10);
-      require_equal(__LINE__, row.beta.is_null(), false);
+      require_equal(__LINE__, row.beta.has_value(), true);
       require_equal(__LINE__, row.beta.value(), "Cookies!");
-      require_equal(__LINE__, row.gamma.is_null(), false);
-      require_equal(__LINE__, row.gamma.value(), true);
+      require_equal(__LINE__, row.gamma, true);
     }
 
     db(update(tab).set(tab.alpha = 20, tab.beta = "Monster", tab.gamma = false).unconditionally());
@@ -95,7 +91,7 @@ int Type(int, char*[])
     {
       require_equal(__LINE__, row.alpha.value(), 20);
       require_equal(__LINE__, row.beta.value(), "Monster");
-      require_equal(__LINE__, row.gamma.value(), false);
+      require_equal(__LINE__, row.gamma, false);
     }
 
     auto prepared_update = db.prepare(
@@ -113,7 +109,7 @@ int Type(int, char*[])
     {
       require_equal(__LINE__, row.alpha.value(), 30);
       require_equal(__LINE__, row.beta.value(), "IceCream");
-      require_equal(__LINE__, row.gamma.value(), true);
+      require_equal(__LINE__, row.gamma, true);
     }
   }
   catch (std::exception& e)

tests/sqlite3/usage/Attach.cpp

@@ -50,7 +50,7 @@ int Attach(int, char*[])
   db.execute(R"(CREATE TABLE tab_sample (
 		alpha INTEGER PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool
 			))");
 
   // Attaching another in-memory database and creating the same table in it
@@ -58,7 +58,7 @@ int Attach(int, char*[])
   db.execute(R"(CREATE TABLE other.tab_sample (
 		alpha INTEGER PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool
 			))");
 
   auto left = TabSample{};

tests/sqlite3/usage/AutoIncrement.cpp

@@ -60,7 +60,8 @@ int AutoIncrement(int, char*[])
   std::set<int64_t> results;
   for (const auto& row : db(select(all_of(tab)).from(tab).unconditionally()))
   {
-    results.insert(row.alpha);
+    if (row.alpha)
+      results.insert(row.alpha.value());
   };
   const auto expected = std::set<int64_t>{1, 2, 3};
   assert(results == expected);

tests/sqlite3/usage/Blob.cpp

@@ -12,7 +12,7 @@
 #include <random>
 
 namespace sql = sqlpp::sqlite3;
-const auto blob = BlobSample{};
+const auto tab = BlobSample{};
 
 /*
  * max default blob/text is 1,000,000,000
@@ -23,34 +23,30 @@ const auto blob = BlobSample{};
 constexpr size_t blob_size = 1000 * 1000ul;
 constexpr size_t blob_small_size = 999;
 
-void verify_blob(sql::connection& db, const std::vector<uint8_t>& data, uint64_t id)
+void verify_blob(sql::connection& db, const std::vector<uint8_t>& expected, uint64_t id)
 {
-  auto result = db(select(blob.data).from(blob).where(blob.id == id));
+  auto result = db(select(tab.data).from(tab).where(tab.id == id));
   const auto& result_row = result.front();
-  std::cerr << "Insert size: " << data.size() << std::endl;
-  std::cerr << "Select size: " << result_row.data.len << std::endl;
-  if (data.size() != result_row.data.len)
+  if (!result_row.data)
+    throw  std::runtime_error("blob data is unpexpectedly NULL for id " + std::to_string(id));
+  const auto received = *result_row.data;
+
+  if (expected.size() != received.size())
   {
     std::cerr << "Size mismatch" << std::endl;
 
-    throw std::runtime_error("Size mismatch " + std::to_string(data.size()) +
-                             " != " + std::to_string(result_row.data.len));
+    throw std::runtime_error("Size mismatch " + std::to_string(expected.size()) +
+                             " != " + std::to_string(received.size()));
   }
   std::cerr << "Verifying content" << std::endl;
-  std::vector<uint8_t> result_blob(result_row.data.blob, result_row.data.blob + result_row.data.len);
-  if (data != result_blob)
+  for (size_t i = 0; i < expected.size(); i++)
   {
-    std::cout << "Content mismatch ([row] original -> received)" << std::endl;
-
-    for (size_t i = 0; i < data.size(); i++)
+    if (expected[i] != received[i])
     {
-      if (data[i] != result_row.data.blob[i])
-      {
-        std::cerr << "[" << i << "] " << static_cast<int>(data.at(i)) << " -> " << static_cast<int>(result_blob.at(i))
-                  << std::endl;
-      }
+      std::cerr << "expected[" << i << "] " << static_cast<int>(expected[i]) << " != received " << static_cast<int>(received[i])
+                << std::endl;
+      throw std::runtime_error("Content mismatch");
     }
-    throw std::runtime_error("Content mismatch");
   }
 }
 
@@ -77,26 +73,20 @@ int Blob(int, char*[])
   std::generate_n(data_smaller.begin(), blob_small_size, generator);
 
   // If we use the bigger blob it will trigger SQLITE_TOOBIG for the query
-  auto id = db(insert_into(blob).set(blob.data = data_smaller));
+  auto id = db(insert_into(tab).set(tab.data = data_smaller));
 
-  auto prepared_insert = db.prepare(insert_into(blob).set(blob.data = parameter(blob.data)));
+  auto prepared_insert = db.prepare(insert_into(tab).set(tab.data = parameter(tab.data)));
   prepared_insert.params.data = data;
-  auto prep_id = db(prepared_insert);
+  const auto prep_id = db(prepared_insert);
   prepared_insert.params.data.set_null();
-  auto null_id = db(prepared_insert);
+  const auto null_id = db(prepared_insert);
 
   verify_blob(db, data_smaller, id);
   verify_blob(db, data, prep_id);
   {
-    auto result = db(select(blob.data).from(blob).where(blob.id == null_id));
+    auto result = db(select(tab.data).from(tab).where(tab.id == null_id));
     const auto& result_row = result.front();
-    std::cerr << "Null blob is_null:\t" << std::boolalpha << result_row.data.is_null() << std::endl;
-    std::cerr << "Null blob len == 0:\t" << std::boolalpha << (result_row.data.len == 0) << std::endl;
-    std::cerr << "Null blob blob == nullptr:\t" << std::boolalpha << (result_row.data.blob == nullptr) << std::endl;
-    if (!result_row.data.is_null() || result_row.data.len != 0 || result_row.data.blob != nullptr)
-    {
-      throw std::runtime_error("Null blob has incorrect values");
-    }
+    std::cerr << "Null blob is_null:\t" << std::boolalpha << (result_row.data == sqlpp::nullopt) << std::endl;
   }
   return 0;
 }

tests/sqlite3/usage/DateTime.cpp

@@ -78,10 +78,8 @@ int DateTime(int, char*[])
 
     for (const auto& row : db(select(all_of(tab)).from(tab).unconditionally()))
     {
-      require_equal(__LINE__, row.colDayPoint.is_null(), true);
-      require_equal(__LINE__, row.colDayPoint.value(), ::sqlpp::chrono::day_point{});
-      require_equal(__LINE__, row.colTimePoint.is_null(), true);
-      require_equal(__LINE__, row.colTimePoint.value(), ::sqlpp::chrono::microsecond_point{});
+      require_equal(__LINE__, row.colDayPoint == sqlpp::nullopt, true);
+      require_equal(__LINE__, row.colTimePoint == sqlpp::nullopt, true);
     }
 
     db(update(tab).set(tab.colDayPoint = today, tab.colTimePoint = now).unconditionally());

tests/sqlite3/usage/DynamicLoadingTest.cpp

@@ -57,7 +57,7 @@ int main()
   db.execute("CREATE TABLE tab_sample (\
         alpha bigint(20) DEFAULT NULL,\
             beta varchar(255) DEFAULT NULL,\
-            gamma bool DEFAULT NULL\
+            gamma bool\
             )");
 
   const auto tab = TabSample{};

tests/sqlite3/usage/DynamicSelect.cpp

@@ -41,6 +41,13 @@
 #include <iostream>
 #include <vector>
 
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const sqlpp::optional<T>& t) {
+  if (not t)
+    return os << "NULL";
+  return os << t.value();
+}
+
 SQLPP_ALIAS_PROVIDER(left)
 
 namespace sql = sqlpp::sqlite3;
@@ -55,7 +62,7 @@ int DynamicSelect(int, char*[])
   db.execute("CREATE TABLE tab_sample (\
 		alpha bigint(20) DEFAULT NULL,\
 			beta varchar(255) DEFAULT NULL,\
-			gamma bool DEFAULT NULL\
+			gamma bool\
 			)");
 
   const auto tab = TabSample{};

tests/sqlite3/usage/FloatingPoint.cpp

@@ -39,15 +39,22 @@ namespace sql = sqlpp::sqlite3;
 
 const auto fp = FpSample{};
 
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const sqlpp::optional<T>& t) {
+  if (not t)
+    return os << "NULL";
+  return os << t.value();
+}
+
 template <typename L, typename R>
 auto require_equal(int line, const L& l, const R& r) -> void
 {
   if (l != r)
   {
     std::cerr << line << ": ";
-    serialize(::sqlpp::wrap_operand_t<L>{l}, std::cerr);
+    std::cerr << l;
     std::cerr << " != ";
-    serialize(::sqlpp::wrap_operand_t<R>{r}, std::cerr);
+    std::cerr << r;
     throw std::runtime_error("Unexpected result");
   }
 }

tests/sqlite3/usage/Sample.cpp

@@ -40,6 +40,13 @@
 SQLPP_ALIAS_PROVIDER(pragma)
 SQLPP_ALIAS_PROVIDER(sub)
 
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const sqlpp::optional<T>& t) {
+  if (not t)
+    return os << "NULL";
+  return os << t.value();
+}
+
 namespace sql = sqlpp::sqlite3;
 int Sample(int, char*[])
 {
@@ -52,7 +59,7 @@ int Sample(int, char*[])
   db.execute(R"(CREATE TABLE tab_sample (
 		alpha INTEGER PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool
 			))");
   db.execute(R"(CREATE TABLE tab_foo (
 		omega bigint(20) DEFAULT NULL
@@ -102,8 +109,8 @@ int Sample(int, char*[])
                                 .from(tab)
                                 .unconditionally()))
   {
-    int64_t x = row.alpha;
-    int64_t a = row.max;
+    sqlpp::optional<int64_t> x = row.alpha;
+    sqlpp::optional<int64_t> a = row.max;
     std::cout << x << ", " << a << std::endl;
   }
   tx.commit();
@@ -134,7 +141,8 @@ int Sample(int, char*[])
   }
 
   std::cerr << "--------" << std::endl;
-  ps.params.alpha = sqlpp::eval<sqlpp::integer>(db, "last_insert_rowid()");
+  const auto last_id = sqlpp::eval<sqlpp::integer>(db, "last_insert_rowid()");
+  ps.params.alpha = last_id.value();
   ps.params.gamma = false;
   for (const auto& row : db(ps))
   {

tests/sqlite3/usage/Select.cpp

@@ -41,6 +41,13 @@
 namespace sql = sqlpp::sqlite3;
 const auto tab = TabSample{};
 
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const sqlpp::optional<T>& t) {
+  if (not t)
+    return os << "NULL";
+  return os << t.value();
+}
+
 void testSelectAll(sql::connection& db, size_t expectedRowCount)
 {
   std::cerr << "--------------------------------------" << std::endl;
@@ -50,7 +57,7 @@ void testSelectAll(sql::connection& db, size_t expectedRowCount)
     ++i;
     std::cerr << ">>> row.alpha: " << row.alpha << ", row.beta: " << row.beta << ", row.gamma: " << row.gamma
               << std::endl;
-    assert(static_cast<size_t>(row.alpha) == i);
+    assert(row.alpha == static_cast<int64_t>(i));
   };
   assert(i == expectedRowCount);
 
@@ -61,7 +68,7 @@ void testSelectAll(sql::connection& db, size_t expectedRowCount)
     ++i;
     std::cerr << ">>> row.alpha: " << row.alpha << ", row.beta: " << row.beta << ", row.gamma: " << row.gamma
               << std::endl;
-    assert(static_cast<size_t>(row.alpha) == i);
+    assert(row.alpha == static_cast<int64_t>(i));
   };
   assert(i == expectedRowCount);
   std::cerr << "--------------------------------------" << std::endl;
@@ -93,7 +100,7 @@ int Select(int, char*[])
   db.execute(R"(CREATE TABLE tab_sample (
 		alpha INTEGER PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool
 			))");
 
   testSelectAll(db, 0);
@@ -141,8 +148,8 @@ int Select(int, char*[])
   auto tx = start_transaction(db);
   for (const auto& row : db(select(all_of(tab), select(max(tab.alpha)).from(tab)).from(tab).unconditionally()))
   {
-    const int64_t x = row.alpha;
-    const int64_t a = row.max;
+    const auto x = row.alpha;
+    const auto a = row.max;
     std::cout << ">>>" << x << ", " << a << std::endl;
   }
   for (const auto& row :
@@ -153,14 +160,14 @@ int Select(int, char*[])
     std::cerr << ">>> row.alpha: " << row.alpha << ", row.beta: " << row.beta << ", row.gamma: " << row.gamma
               << ", row.trim: '" << row.trim << "'" << std::endl;
     // check trim
-    assert(string_util::trim(row.beta.value()) == row.trim.value());
+    assert((not row.beta and not row.trim) || string_util::trim(std::string(row.beta.value())) == row.trim.value());
     // end
   };
 
   for (const auto& row : db(select(all_of(tab), select(trim(tab.beta)).from(tab)).from(tab).unconditionally()))
   {
-    const int64_t x = row.alpha;
-    const std::string a = row.trim;
+    const sqlpp::optional<int64_t> x = row.alpha;
+    const sqlpp::optional<sqlpp::string_view> a = row.trim;
     std::cout << ">>>" << x << ", " << a << std::endl;
   }
 

tests/sqlite3/usage/TabSample.sql

@@ -1,5 +1,5 @@
 CREATE TABLE tab_sample (
   alpha bigint(20) DEFAULT NULL,
   beta tinyint(1) DEFAULT NULL,
-  gamma varchar(255) DEFAULT NULL
+  gamma varchar(255)
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

tests/sqlite3/usage/Union.cpp

@@ -37,6 +37,13 @@
 namespace sql = sqlpp::sqlite3;
 const auto tab = TabSample{};
 
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const sqlpp::optional<T>& t) {
+  if (not t)
+    return os << "NULL";
+  return os << t.value();
+}
+
 int Union(int, char*[])
 {
   sql::connection_config config;
@@ -48,7 +55,7 @@ int Union(int, char*[])
   db.execute(R"(CREATE TABLE tab_sample (
 		alpha INTEGER PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool
 			))");
 
   auto u = select(all_of(tab)).from(tab).unconditionally().union_all(select(all_of(tab)).from(tab).unconditionally());

tests/sqlite3/usage/With.cpp

@@ -39,6 +39,13 @@
 namespace sql = sqlpp::sqlite3;
 const auto tab = TabSample{};
 
+template <typename T>
+std::ostream& operator<<(std::ostream& os, const sqlpp::optional<T>& t) {
+  if (not t)
+    return os << "NULL";
+  return os << t.value();
+}
+
 int With(int, char*[])
 {
 #if SQLITE_VERSION_NUMBER >= 3008003
@@ -51,7 +58,7 @@ int With(int, char*[])
   db.execute(R"(CREATE TABLE tab_sample (
 		alpha INTEGER PRIMARY KEY,
 			beta varchar(255) DEFAULT NULL,
-			gamma bool DEFAULT NULL
+			gamma bool
 			))");
 
   auto a = sqlpp::cte(sqlpp::alias::a).as(select(all_of(tab)).from(tab).where(tab.alpha > 3));