Unwrap nullable types in PropertyHelper prior to looking up properties

Fixes #721

src/Microsoft.AspNet.Mvc.Common/PropertyHelper.cs

@@ -198,6 +198,10 @@ namespace Microsoft.AspNet.Mvc
             Func<PropertyInfo, PropertyHelper> createPropertyHelper,
             ConcurrentDictionary<Type, PropertyHelper[]> cache)
         {
+            // Unwrap nullable types. This means Nullable<T>.Value and Nullable<T>.HasValue will not be
+            // part of the sequence of properties returned by this method.
+            type = Nullable.GetUnderlyingType(type) ?? type;
+
             // Using an array rather than IEnumerable, as target will be called on the hot path numerous times.
             PropertyHelper[] helpers;
 

test/Microsoft.AspNet.Mvc.Core.Test/PropertyHelperTest.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Linq;
 using System.Reflection;
 using Xunit;
@@ -114,6 +115,32 @@ namespace Microsoft.AspNet.Mvc
             Assert.Equal("Prop6", helper.Name);
         }
 
+        [Theory]
+        [InlineData(typeof(int?))]
+        [InlineData(typeof(DayOfWeek?))]
+        public void PropertyHelper_WorksForNullablePrimitiveAndEnumTypes(Type nullableType)
+        {
+            // Act
+            var properties = PropertyHelper.GetProperties(nullableType);
+
+            // Assert
+            Assert.Empty(properties);
+        }
+
+        [Fact]
+        public void PropertyHelper_UnwrapsNullableTypes()
+        {
+            // Arrange
+            var myType = typeof(MyStruct?);
+
+            // Act
+            var properties = PropertyHelper.GetProperties(myType);
+
+            // Assert
+            var property = Assert.Single(properties);
+            Assert.Equal("Foo", property.Name);
+        }
+
         [Fact]
         public void PropertyHelper_WorksForStruct()
         {
@@ -350,5 +377,10 @@ namespace Microsoft.AspNet.Mvc
 
             public static string NotVisible4 { get; set; }
         }
+
+        private struct MyStruct
+        {
+            public string Foo { get; set; }
+        }
     }
 }