Adjust DateTime parameters

Author: hazzik

src/NHibernate.Test/TypesTest/AbstractDateTimeTypeFixture.cs

@@ -548,7 +548,7 @@ protected DateTimeKind GetTypeKind()
 		}
 	}
 
-	public class ClientDriverWithParamsStats : IDriver
+	public class ClientDriverWithParamsStats : IDriver, IParameterAdjuster
 	{
 		private readonly Dictionary<SqlType, int> _usedSqlTypes = new Dictionary<SqlType, int>();
 		private readonly Dictionary<DbType, int> _usedDbTypes = new Dictionary<DbType, int>();
@@ -679,5 +679,11 @@ void IDriver.AdjustCommand(DbCommand command)
 		DateTime IDriver.MinDate => _driverImplementation.MinDate;
 
 		#endregion
+
+		public void AdjustParameterForValue(DbParameter parameter, SqlType sqlType, object value)
+		{
+			var adjustingDriver = _driverImplementation as IParameterAdjuster;
+			adjustingDriver?.AdjustParameterForValue(parameter, sqlType, value);
+		}
 	}
 }

src/NHibernate/Driver/NpgsqlDriver.cs

@@ -1,6 +1,8 @@
+using System;
 using System.Data;
 using System.Data.Common;
 using NHibernate.AdoNet;
+using NHibernate.SqlTypes;
 
 namespace NHibernate.Driver
 {
@@ -25,7 +27,7 @@ namespace NHibernate.Driver
 	/// <a href="http://pgfoundry.org/projects/npgsql">http://pgfoundry.org/projects/npgsql</a>. 
 	/// </p>
 	/// </remarks>
-	public class NpgsqlDriver : ReflectionBasedDriver, IEmbeddedBatcherFactoryProvider
+	public class NpgsqlDriver : ReflectionBasedDriver, IEmbeddedBatcherFactoryProvider, IParameterAdjuster
 	{
 		/// <summary>
 		/// Initializes a new instance of the <see cref="NpgsqlDriver"/> class.
@@ -74,10 +76,19 @@ protected override void InitializeParameter(DbParameter dbParam, string name, Sq
 
 		// Prior to v3, Npgsql was expecting DateTime for time.
 		// https://github.com/npgsql/npgsql/issues/347
-		public override bool RequiresTimeSpanForTime => (DriverVersion?.Major ?? 3) >= 3;
+		public override bool RequiresTimeSpanForTime => DriverVersionMajor >= 3;
+
+		private int DriverVersionMajor => DriverVersion?.Major ?? 3;
 
 		public override bool HasDelayedDistributedTransactionCompletion => true;
 
 		System.Type IEmbeddedBatcherFactoryProvider.BatcherFactoryClass => typeof(GenericBatchingBatcherFactory);
+		public void AdjustParameterForValue(DbParameter parameter, SqlType sqlType, object value)
+		{
+			if (DriverVersionMajor >= 6 && sqlType.DbType == DbType.DateTime && value is DateTime time && time.Kind != DateTimeKind.Utc)
+			{
+				parameter.DbType = DbType.DateTime2;
+			}
+		}
 	}
 }

src/NHibernate/Type/AbstractDateTimeType.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Data.Common;
 using System.Globalization;
+using NHibernate.Driver;
 using NHibernate.Engine;
 using NHibernate.SqlTypes;
 
@@ -90,7 +91,13 @@ public override void Set(DbCommand st, object value, int index, ISessionImplemen
 			// hour with daylight shift to be always wrongly converted. So better just fail.
 			if (Kind != DateTimeKind.Unspecified && dateValue.Kind != Kind)
 				throw new ArgumentException($"{Name} expect date kind {Kind} but it is {dateValue.Kind}", nameof(value));
-			st.Parameters[index].Value = AdjustDateTime(dateValue);
+
+			var parameter = st.Parameters[index];
+
+			//Allow the driver to adjust the parameter for the value
+			var adjustedValue = AdjustDateTime(dateValue);
+			session.Factory.ConnectionProvider.Driver.AdjustParameterForValue(parameter, SqlType, adjustedValue);
+			parameter.Value = adjustedValue;
 		}
 
 		#region IVersionType Members