[Codeplex #2162]: Nullable Enum support in Web API

This fix is to allow nullable enums as function paramters.

OData/src/System.Web.OData/OData/Formatter/ODataModelBinderProvider.cs

@@ -120,8 +120,13 @@ namespace System.Web.OData.Formatter
                         valueString = values[1];
                     }
 
+                    if (type.IsNullable() && String.Equals(valueString, "null", StringComparison.Ordinal))
+                    {
+                        return null;
+                    }
+
                     Type enumType = TypeHelper.GetUnderlyingTypeOrSelf(type);
-                    object[] parameters = new[] { valueString, Enum.ToObject(type, 0) };
+                    object[] parameters = new[] { valueString, Enum.ToObject(enumType, 0) };
                     bool isSuccessful = (bool)enumTryParseMethod.MakeGenericMethod(enumType).Invoke(null, parameters);
 
                     if (!isSuccessful)

OData/test/System.Web.OData.Test/OData/EnumSerializerTest.cs

@@ -8,6 +8,7 @@ using System.Web.OData.Extensions;
 using System.Web.OData.Formatter;
 using System.Web.OData.Formatter.Deserialization;
 using System.Web.OData.Formatter.Serialization;
+using System.Web.OData.Routing;
 using Microsoft.OData.Core;
 using Microsoft.OData.Edm;
 using Microsoft.OData.Edm.Library;
@@ -114,6 +115,52 @@ namespace System.Web.OData
             JsonAssert.Equal(Resources.EnumComplexType, content.ReadAsStringAsync().Result);
         }
 
+        [Fact]
+        public void NullableEnumParameter_Works_WithNotNullEnumValue()
+        {
+            // Arrange
+            const string expect =
+                "{\r\n" +
+                "  \"@odata.context\":\"http://localhost/odata/$metadata#Edm.Boolean\",\"value\":true\r\n" +
+                "}";
+
+            HttpConfiguration config = new[] { typeof(NullableEnumValueController) }.GetHttpConfiguration();
+            config.MapODataServiceRoute("odata", "odata", GetSampleModel());
+            HttpClient client = new HttpClient(new HttpServer(config));
+
+            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get,
+                "http://localhost/odata/NullableEnumFunction(ColorParameter=System.Web.OData.Builder.TestModels.Color'Red')");
+
+            // Act
+            HttpResponseMessage respone = client.SendAsync(request).Result;
+
+            // Assert
+            Assert.Equal(expect, respone.Content.ReadAsStringAsync().Result);
+        }
+
+        [Fact]
+        public void NullableEnumParameter_Works_WithNullEnumValue()
+        {
+            // Arrange
+            const string expect =
+                "{\r\n" +
+                "  \"@odata.context\":\"http://localhost/odata/$metadata#Edm.Boolean\",\"value\":false\r\n" +
+                "}";
+
+            HttpConfiguration config = new[] { typeof(NullableEnumValueController) }.GetHttpConfiguration();
+            config.MapODataServiceRoute("odata", "odata", GetSampleModel());
+            HttpClient client = new HttpClient(new HttpServer(config));
+
+            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get,
+                "http://localhost/odata/NullableEnumFunction(ColorParameter=null)");
+
+            // Act
+            HttpResponseMessage respone = client.SendAsync(request).Result;
+
+            // Assert
+            Assert.Equal(expect, respone.Content.ReadAsStringAsync().Result);
+        }
+
         private static ODataMediaTypeFormatter GetFormatter()
         {
             var formatter = new ODataMediaTypeFormatter(new ODataPayloadKind[] { ODataPayloadKind.Property })
@@ -140,6 +187,10 @@ namespace System.Web.OData
         {
             ODataConventionModelBuilder builder = new ODataConventionModelBuilder();
             builder.ComplexType<EnumComplex>();
+
+            FunctionConfiguration function = builder.Function("NullableEnumFunction").Returns<bool>();
+            function.Parameter<Color?>("ColorParameter");
+
             return builder.GetEdmModel();
         }
 
@@ -150,4 +201,21 @@ namespace System.Web.OData
             public Color UndefinedColor { get; set; }
         }
     }
-}
+
+    public class NullableEnumValueController : ODataController
+    {
+        [HttpGet]
+        [ODataRoute("NullableEnumFunction(ColorParameter={colorParameter})")]
+        [EnableQuery]
+        public bool NullableEnumFunction([FromODataUri]Color? colorParameter)
+        {
+            if (colorParameter != null)
+            {
+                return true;
+            }
+
+            Assert.True(ModelState.IsValid);
+            return false;
+        }
+    }
+}

OData/test/System.Web.OData.Test/OData/Formatter/ODataModelBinderProviderTest.cs

@@ -242,6 +242,36 @@ namespace System.Web.OData.Formatter
                 response.Content.ReadAsAsync(value.GetType(), configuration.Formatters).Result);
         }
 
+        [Theory]
+        [InlineData(null, false)]
+        [InlineData(FlagsEnum.One, true)]
+        public void ODataModelBinderProvider_Works_ForNullableEnum(object value, bool expect)
+        {
+            // Arrange
+            HttpConfiguration configuration = new HttpConfiguration();
+            configuration.Services.Replace(typeof(ModelBinderProvider), new ODataModelBinderProvider());
+            configuration.MapODataServiceRoute("odata", "", GetEdmModel());
+
+            var controllers = new[] { typeof(ODataModelBinderProviderTestODataController) };
+            TestAssemblyResolver resolver = new TestAssemblyResolver(new MockAssembly(controllers));
+            configuration.Services.Replace(typeof(IAssembliesResolver), resolver);
+
+            HttpServer server = new HttpServer(configuration);
+            HttpClient client = new HttpClient(server);
+
+            // Act 
+            string url = String.Format(
+                "http://localhost/GetNullableFlagsEnum(flagsEnum={0})", 
+                value == null ? "null" : Uri.EscapeDataString(ConventionsHelpers.GetUriRepresentationForValue(value)));
+            HttpResponseMessage response = client.GetAsync(url).Result;
+
+            // Assert
+            response.EnsureSuccessStatusCode();
+            Assert.Equal(
+                expect,
+                response.Content.ReadAsAsync(typeof(bool), configuration.Formatters).Result);
+        }
+
         [Theory]
         [InlineData("abc", "GetEnum", "simpleEnum")]
         public void ResourceIsNotFound_IfContainsInvalidEnum(object value, string action, string parameterName)
@@ -282,6 +312,9 @@ namespace System.Web.OData.Formatter
             getFlagsEnum.Parameter<FlagsEnum>("flagsEnum");
             getFlagsEnum.Returns<FlagsEnum>();
 
+            FunctionConfiguration function = builder.Function("GetNullableFlagsEnum").Returns<bool>();
+            function.Parameter<FlagsEnum?>("flagsEnum");
+
             return builder.GetEdmModel();
         }
     }
@@ -488,5 +521,17 @@ namespace System.Web.OData.Formatter
             return flagsEnum;
         }
 
+        [HttpGet]
+        [ODataRoute("GetNullableFlagsEnum(flagsEnum={flagsEnum})")]
+        public bool GetNullableFlagsEnum(FlagsEnum? flagsEnum)
+        {
+            if (flagsEnum != null)
+            {
+                return true;
+            }
+
+            Assert.True(ModelState.IsValid);
+            return false;
+        }
     }
 }