Change to GetAll to allow the usage of a nullable type in T when T is an interface… #933 (#936)

* Change to GetAll to allow the usage of a nullable type in T when T is an interface.

* Change to GetAll to allow the usage of a nullable type in T when T is an interface: further change to check if val == null and if so then don't try to assign it as a property value.

* Change to Get to allow the usage of a nullable type in T when T is an interface. (effectively the same change as the previous change to GetAll.)

* Change to GetAsync and GetAllAsync to allow the usage of a nullable type in T when T is  an interface.

* Added in UserWithNullableDob and IUserWithNullableDob.

Added in tests for GetAndGetAllWithNullableValues and  GetAsyncAndGetAllAsyncWithNullableValues.

* Added in .ConfigureAwait(false) in the GetAsync Test.
Added comment to identify which issue the test relates to.

* Added NullableDates tables to the test databases.
Adjusted variable names in GetAndGetAllWithNullableValues and GetAsyncAndGetAllAsyncWithNullableValues.

* Changed IUserWithNullableDob to INullableDate.

Dapper.Contrib/SqlMapperExtensions.Async.cs

@@ -50,7 +50,16 @@ public static partial class SqlMapperExtensions
             foreach (var property in TypePropertiesCache(type))
             {
                 var val = res[property.Name];
-                property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                if (val == null) continue;
+                if (property.PropertyType.IsGenericType() && property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
+                {
+                    var genericType = Nullable.GetUnderlyingType(property.PropertyType);
+                    if (genericType != null) property.SetValue(obj, Convert.ChangeType(val, genericType), null);
+                }
+                else
+                {
+                    property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                }
             }
 
             ((IProxy)obj).IsDirty = false;   //reset change tracking and return
@@ -100,7 +109,16 @@ public static partial class SqlMapperExtensions
                 foreach (var property in TypePropertiesCache(type))
                 {
                     var val = res[property.Name];
-                    property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                    if (val == null) continue;
+                    if (property.PropertyType.IsGenericType() && property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
+                    {
+                        var genericType = Nullable.GetUnderlyingType(property.PropertyType);
+                        if (genericType != null) property.SetValue(obj, Convert.ChangeType(val, genericType), null);
+                    }
+                    else
+                    {
+                        property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                    }
                 }
                 ((IProxy)obj).IsDirty = false;   //reset change tracking and return
                 list.Add(obj);

Dapper.Contrib/SqlMapperExtensions.cs

@@ -202,7 +202,16 @@ private static PropertyInfo GetSingleKey<T>(string method)
                 foreach (var property in TypePropertiesCache(type))
                 {
                     var val = res[property.Name];
-                    property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                    if (val == null) continue;
+                    if (property.PropertyType.IsGenericType() && property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
+                    {
+                        var genericType = Nullable.GetUnderlyingType(property.PropertyType);
+                        if (genericType != null) property.SetValue(obj, Convert.ChangeType(val, genericType), null);
+                    }
+                    else
+                    {
+                        property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                    }
                 }
 
                 ((IProxy)obj).IsDirty = false;   //reset change tracking and return
@@ -249,7 +258,16 @@ private static PropertyInfo GetSingleKey<T>(string method)
                 foreach (var property in TypePropertiesCache(type))
                 {
                     var val = res[property.Name];
-                    property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                    if (val == null) continue;
+                    if (property.PropertyType.IsGenericType() && property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
+                    {
+                        var genericType = Nullable.GetUnderlyingType(property.PropertyType);
+                        if (genericType != null) property.SetValue(obj, Convert.ChangeType(val, genericType), null);
+                    }
+                    else
+                    {
+                        property.SetValue(obj, Convert.ChangeType(val, property.PropertyType), null);
+                    }
                 }
                 ((IProxy)obj).IsDirty = false;   //reset change tracking and return
                 list.Add(obj);

Dapper.Tests.Contrib/TestSuite.Async.cs

@@ -355,6 +355,30 @@ public async Task GetAllAsync()
             }
         }
 
+        /// <summary>
+        /// Test for issue #933
+        /// </summary>
+        [Fact]
+        public async void GetAsyncAndGetAllAsyncWithNullableValues()
+        {
+            using (var connection = GetOpenConnection())
+            {
+                var id1 = connection.Insert(new NullableDate { DateValue = new DateTime(2011, 07, 14) });
+                var id2 = connection.Insert(new NullableDate { DateValue = null });
+
+                var value1 = await connection.GetAsync<INullableDate>(id1).ConfigureAwait(false);
+                Assert.Equal(new DateTime(2011, 07, 14), value1.DateValue.Value);
+
+                var value2 = await connection.GetAsync<INullableDate>(id2).ConfigureAwait(false);
+                Assert.True(value2.DateValue == null);
+
+                var value3 = await connection.GetAllAsync<INullableDate>().ConfigureAwait(false);
+                var valuesList = value3.ToList();
+                Assert.Equal(new DateTime(2011, 07, 14), valuesList[0].DateValue.Value);
+                Assert.True(valuesList[1].DateValue == null);
+            }
+        }
+
         [Fact]
         public async Task InsertFieldWithReservedNameAsync()
         {

Dapper.Tests.Contrib/TestSuite.cs

@@ -53,6 +53,19 @@ public class User : IUser
         public int Age { get; set; }
     }
 
+    public interface INullableDate
+    {
+        [Key]
+        int Id { get; set; }
+        DateTime? DateValue { get; set; }
+    }
+
+    public class NullableDate : INullableDate
+    {
+        public int Id { get; set; }
+        public DateTime? DateValue { get; set; }
+    }
+
     public class Person
     {
         public int Id { get; set; }
@@ -543,6 +556,29 @@ public void GetAll()
             }
         }
 
+        /// <summary>
+        /// Test for issue #933
+        /// </summary>
+        [Fact]
+        public void GetAndGetAllWithNullableValues()
+        {
+            using (var connection = GetOpenConnection())
+            {
+                var id1 = connection.Insert(new NullableDate { DateValue = new DateTime(2011, 07, 14) });
+                var id2 = connection.Insert(new NullableDate { DateValue = null });
+
+                var value1 = connection.Get<INullableDate>(id1);
+                Assert.Equal(new DateTime(2011, 07, 14), value1.DateValue.Value);
+
+                var value2 = connection.Get<INullableDate>(id2);
+                Assert.True(value2.DateValue == null);
+
+                var value3 = connection.GetAll<INullableDate>().ToList();
+                Assert.Equal(new DateTime(2011, 07, 14), value3[0].DateValue.Value);
+                Assert.True(value3[1].DateValue == null);
+            }
+        }
+
         [Fact]
         public void Transactions()
         {

Dapper.Tests.Contrib/TestSuites.cs

@@ -57,6 +57,8 @@ static SqlServerTestSuite()
                 connection.Execute("CREATE TABLE ObjectZ (Id int not null, Name nvarchar(100) not null);");
                 dropTable("GenericType");
                 connection.Execute("CREATE TABLE GenericType (Id nvarchar(100) not null, Name nvarchar(100) not null);");
+                dropTable("NullableDates");
+                connection.Execute("CREATE TABLE NullableDates (Id int IDENTITY(1,1) not null, DateValue DateTime null);");
             }
         }
     }
@@ -106,6 +108,8 @@ static MySqlServerTestSuite()
                     connection.Execute("CREATE TABLE ObjectZ (Id int not null, Name nvarchar(100) not null);");
                     dropTable("GenericType");
                     connection.Execute("CREATE TABLE GenericType (Id nvarchar(100) not null, Name nvarchar(100) not null);");
+                    dropTable("NullableDates");
+                    connection.Execute("CREATE TABLE NullableDates (Id int not null AUTO_INCREMENT PRIMARY KEY, DateValue DateTime);");
                 }
             }
             catch (MySqlException e)
@@ -142,6 +146,7 @@ static SQLiteTestSuite()
                 connection.Execute("CREATE TABLE ObjectY (ObjectYId integer not null, Name nvarchar(100) not null) ");
                 connection.Execute("CREATE TABLE ObjectZ (Id integer not null, Name nvarchar(100) not null) ");
                 connection.Execute("CREATE TABLE GenericType (Id nvarchar(100) not null, Name nvarchar(100) not null) ");
+                connection.Execute("CREATE TABLE NullableDates (Id integer primary key autoincrement not null, DateValue DateTime) ");
             }
         }
     }
@@ -173,6 +178,7 @@ static SqlCETestSuite()
                 connection.Execute(@"CREATE TABLE ObjectY (ObjectYId int not null, Name nvarchar(100) not null) ");
                 connection.Execute(@"CREATE TABLE ObjectZ (Id int not null, Name nvarchar(100) not null) ");
                 connection.Execute(@"CREATE TABLE GenericType (Id nvarchar(100) not null, Name nvarchar(100) not null) ");
+                connection.Execute(@"CREATE TABLE NullableDates (Id int IDENTITY(1,1) not null, DateValue DateTime null) ");
             }
             Console.WriteLine("Created database");
         }