Implemented get/set_default_isolation_level() functions to change the

transaction isolation level default per-connection

connector_api/connection.h

@@ -130,8 +130,19 @@ namespace sqlpp
         return t._prepare(*this);
       }
 
+
+      //! set the transaction isolation level for the current connection
+      /// time of effect is connector-specific, for most is will only affect new transactions
+      void set_default_isolation_level(sqlpp::isolation_level);
+
+      //! read the default transaction isolation level for the current connection
+      sqlpp::isolation_level get_default_isolation_level();
+
       //! start transaction
-      void start_transaction(isolation_level isolation = isolation_level::undefined);
+      void start_transaction();
+
+      //! start transaction with defined isolation level (optional only for connectors that support it)
+      void start_transaction(isolation_level isolation /* = isolation_level::undefined */);
 
       //! commit transaction (or throw transaction if the transaction has been finished already)
       void commit_transaction();

tests/MockDb.h

@@ -38,6 +38,7 @@
 // an object to store internal Mock flags and values to validate in tests
 struct InternalMockData {
     sqlpp::isolation_level _last_isolation_level;
+    sqlpp::isolation_level _default_isolation_level;
 };
 
 template <bool enforceNullResultTreatment>
@@ -251,12 +252,26 @@ struct MockDbT : public sqlpp::connection
     return {name};
   }
 
+  void start_transaction()
+  {
+      _mock_data._last_isolation_level = _mock_data._default_isolation_level;
+  }
+
   void start_transaction(sqlpp::isolation_level level)
   {
-    // store temporarily to verify the expected level was used in testcases
     _mock_data._last_isolation_level = level;
   }
 
+  void set_default_isolation_level(sqlpp::isolation_level level)
+  {
+      _mock_data._default_isolation_level = level;
+  }
+
+  sqlpp::isolation_level get_default_isolation_level()
+  {
+      return _mock_data._default_isolation_level;
+  }
+
   void rollback_transaction(bool)
   {}
 
@@ -266,6 +281,7 @@ struct MockDbT : public sqlpp::connection
   void report_rollback_failure(std::string)
   {}
 
+  // temporary data store to verify the expected results were produced
   InternalMockData _mock_data;
 };
 

tests/Select.cpp

@@ -183,8 +183,22 @@ int Select(int, char* [])
     for_each_field(row, to_cerr{});
   }
 
+  {
       auto transaction = start_transaction(db, sqlpp::isolation_level::read_committed);
-  std::cout << (db._mock_data._last_isolation_level == sqlpp::isolation_level::read_committed) << std::endl;
+      if (db._mock_data._last_isolation_level != sqlpp::isolation_level::read_committed)
+      {
+          std::cout << "Error: transaction isolation level does not match expacted level" << std::endl;
+      }
+
+  }
+  db.set_default_isolation_level(sqlpp::isolation_level::read_uncommitted);
+  {
+      auto transaction = start_transaction(db);
+      if (db._mock_data._last_isolation_level != sqlpp::isolation_level::read_uncommitted)
+      {
+          std::cout << "Error: transaction isolation level does not match default level" << std::endl;
+      }
+  }
 
   return 0;
 }