Merge pull request #2640 from lbargaoanu/dynamic_mapping_null

Dynamic mapping : Map null to the default for value types

Author: jbogard

src/AutoMapper/Internal/ReflectionHelper.cs

@@ -32,7 +32,7 @@ public static object MapMember(ResolutionContext context, MemberInfo member, obj
         {
             var memberType = GetMemberType(member);
             var destValue = destination == null ? null : GetMemberValue(member, destination);
-            return context.Map(value, destValue, value?.GetType() ?? memberType, memberType, PropertyMap.Default);
+            return context.Map(value, destValue, value?.GetType() ?? typeof(object), memberType, PropertyMap.Default);
         }
 
         public static bool IsDynamic(object obj) => obj is IDynamicMetaObjectProvider;

src/UnitTests/Mappers/DynamicMapperTests.cs

@@ -12,6 +12,7 @@ class Destination
         public string Bar { get; set; }
         internal string Jack { get; set; }
         public int[] Data { get; set; }
+        public int Baz { get; set; }
     }
 
     public class DynamicDictionary : DynamicObject
@@ -63,10 +64,11 @@ public void Should_map_source_properties()
         {
             var config = new MapperConfiguration(cfg => { });
             var data = new[] { 1, 2, 3 };
-            _destination = config.CreateMapper().Map<DynamicDictionary>(new Destination { Foo = "Foo", Bar = "Bar", Data = data });
-            ((int)_destination.Count).ShouldBe(3);
+            _destination = config.CreateMapper().Map<DynamicDictionary>(new Destination { Foo = "Foo", Bar = "Bar", Data = data, Baz = 12 });
+            ((int)_destination.Count).ShouldBe(4);
             Assert.Equal("Foo", _destination.Foo);
             Assert.Equal("Bar", _destination.Bar);
+            Assert.Equal(12, _destination.Baz);
             ((int[])_destination.Data).SequenceEqual(data).ShouldBeTrue();
         }
     }
@@ -130,6 +132,24 @@ public void Should_map_existing_properties()
             _destination.Foo.ShouldBe("Foo");
             _destination.Bar.ShouldBeNull();
         }
+    }
+
+    public class When_mapping_from_dynamic_null_to_int
+    {
+        Destination _destination;
+
+        [Fact]
+        public void Should_map_to_zero()
+        {
+            dynamic source = new DynamicDictionary();
+            source.Foo = "Foo";
+            source.Baz = null;
+            var config = new MapperConfiguration(cfg => { });
+            _destination = config.CreateMapper().Map<Destination>(source);
+            _destination.Foo.ShouldBe("Foo");
+            _destination.Bar.ShouldBeNull();
+            _destination.Baz.ShouldBe(0);
+        }
     }
 
     public class When_mapping_from_dynamic_to_dynamic

src/UnitTests/Mappers/StringDictionaryMapperTests.cs

@@ -9,6 +9,7 @@ class Destination
     {
         public string Foo { get; set; }
         public string Bar { get; set; }
+        public int Baz { get; set; }
     }
 
     public class When_mapping_to_StringDictionary : NonValidatingSpecBase
@@ -47,6 +48,7 @@ public void Should_map_destination_properties()
         {
             _destination.Foo.ShouldBe("Foo");
             _destination.Bar.ShouldBe("Bar");
+            _destination.Baz.ShouldBe(0);
         }
     }
 
@@ -93,6 +95,28 @@ public void Should_map_existing_properties()
         {
             _destination.Foo.ShouldBe("Foo");
             _destination.Bar.ShouldBeNull();
+            _destination.Baz.ShouldBe(0);
+        }
+    }
+
+    public class When_mapping_from_StringDictionary_null_to_int : NonValidatingSpecBase
+    {
+        Destination _destination;
+
+        protected override MapperConfiguration Configuration { get; } = new MapperConfiguration(cfg => { });
+
+        protected override void Because_of()
+        {
+            var source = new StringDictionary() { { "Foo", "Foo" }, { "Baz", null } };
+            _destination = Mapper.Map<Destination>(source);
+        }
+
+        [Fact]
+        public void Should_map_to_zero()
+        {
+            _destination.Foo.ShouldBe("Foo");
+            _destination.Bar.ShouldBeNull();
+            _destination.Baz.ShouldBe(0);
         }
     }