GH-3530: Add a mechanism to override the default DbDataReader returned from executing a command.

Author: David Ellingsworth

src/NHibernate.Test/NHSpecificTest/GH1547/Fixture.cs

@@ -184,6 +184,11 @@ DbConnection IDriver.CreateConnection()
 			return _driverImplementation.CreateConnection();
 		}
 
+		DbDataReader IDriver.ExecuteReader(DbCommand cmd)
+		{
+			return _driverImplementation.ExecuteReader(cmd);
+		}
+
 		bool IDriver.SupportsMultipleOpenReaders => _driverImplementation.SupportsMultipleOpenReaders;
 
 		void IDriver.PrepareCommand(DbCommand command)

src/NHibernate.Test/TypesTest/AbstractDateTimeTypeFixture.cs

@@ -601,6 +601,11 @@ DbParameter IDriver.GenerateParameter(DbCommand command, string name, SqlType sq
 			return param;
 		}
 
+		DbDataReader IDriver.ExecuteReader(DbCommand cmd)
+		{
+			return _driverImplementation.ExecuteReader(cmd);
+		}
+
 		#region Firebird mess
 
 		public void CleanUp()

src/NHibernate/AdoNet/AbstractBatcher.cs

@@ -252,13 +252,16 @@ private DbDataReader DoExecuteReader(DbCommand cmd)
 		{
 			try
 			{
-				var reader = cmd.ExecuteReader();
+				var driver = _factory.ConnectionProvider.Driver;
+				var reader = driver.ExecuteReader(cmd);
+
 				if (reader == null)
 				{
 					// MySql may return null instead of an exception, by example when the query is canceled by another thread.
 					throw new InvalidOperationException("The query execution has yielded a null reader. (Has it been canceled?)");
 				}
-				return _factory.ConnectionProvider.Driver.SupportsMultipleOpenReaders
+
+				return driver.SupportsMultipleOpenReaders
 					? reader
 					: NHybridDataReader.Create(reader);
 			}

src/NHibernate/Driver/DriverBase.cs

@@ -361,5 +361,17 @@ public DbParameter GenerateOutputParameter(DbCommand command)
 		/// Get the timeout in seconds for ADO.NET queries.
 		/// </summary>
 		public virtual int CommandTimeout => commandTimeout;
+
+		/// <summary>
+		/// Provides a mechanism to override the default DbDataReader used
+		/// by a data provider. Some providers don't provide a DataReader
+		/// that implement all of the methods.
+		/// </summary>
+		/// <param name="cmd">The command to execute.</param>
+		/// <returns>A <see cref="DbDataReader">DbDataReader</see> object.</returns>
+		public virtual DbDataReader ExecuteReader(DbCommand cmd)
+		{
+			return cmd.ExecuteReader();
+		}
 	}
 }

src/NHibernate/Driver/IDriver.cs

@@ -163,5 +163,14 @@ public interface IDriver
 		/// The minimal date supplied as a <see cref="DateTime" /> supported by this driver.
 		/// </summary>
 		DateTime MinDate { get; }
+
+		/// <summary>
+		/// Provides a mechanism to override the default DbDataReader used
+		/// by a data provider. Some providers don't provide a DataReader
+		/// that implement all of the methods.
+		/// </summary>
+		/// <param name="cmd">The command to execute.</param>
+		/// <returns>A <see cref="DbDataReader">DbDataReader</see> object.</returns>
+		DbDataReader ExecuteReader(DbCommand cmd);
 	}
 }