fixes #931: Undeclared enum type value for untype value serialized as empty resource (#961)

* fixes #931: Undeclared enum type value for untype value serialized as empty resource

* Update the comments.

Author: xuzhg

src/Microsoft.AspNetCore.OData/Formatter/Serialization/ODataResourceSerializer.cs

@@ -638,6 +638,7 @@ public virtual void AppendDynamicProperties(ODataResource resource, SelectExpand
 
             IEdmStructuredType structuredType = resourceContext.StructuredType;
             IEdmStructuredObject structuredObject = resourceContext.EdmObject;
+            ODataSerializerContext serializierContext = resourceContext.SerializerContext;
             object value;
             IDelta delta = structuredObject as IDelta;
             if (structuredObject is EdmUntypedObject untypedObject) // NO CLR, NO EDM
@@ -700,10 +701,25 @@ public virtual void AppendDynamicProperties(ODataResource resource, SelectExpand
                     continue;
                 }
 
-                IEdmTypeReference edmTypeReference = resourceContext.SerializerContext.GetEdmType(dynamicPropertyValue,
-                    dynamicPropertyValue.GetType(), true);
+                Type propertyType = dynamicPropertyValue.GetType();
+                IEdmTypeReference edmTypeReference = serializierContext.GetEdmType(dynamicPropertyValue, propertyType, true);
                 if (edmTypeReference == null || edmTypeReference.IsStructuredOrUntyped())
                 {
+                    if (TypeHelper.IsEnum(propertyType))
+                    {
+                        // we don't have the Edm enum type in the model, let's write it as string.
+                        dynamicProperties.Add(new ODataProperty
+                        {
+                            Name = dynamicProperty.Key,
+
+                            // TBD: Shall we write the un-declared enum value as full-name string?
+                            // So, "Data":"Apple"  => should be ""Data":"Namespace.EnumTypeName.Apple" ?
+                            Value = dynamicPropertyValue.ToString()
+                        });
+
+                        continue;
+                    }
+
                     resourceContext.AppendDynamicOrUntypedProperty(dynamicProperty.Key, dynamicPropertyValue);
                 }
                 else
@@ -716,7 +732,7 @@ public virtual void AppendDynamicProperties(ODataResource resource, SelectExpand
                     }
 
                     dynamicProperties.Add(propertySerializer.CreateProperty(
-                        dynamicPropertyValue, edmTypeReference, dynamicProperty.Key, resourceContext.SerializerContext));
+                        dynamicPropertyValue, edmTypeReference, dynamicProperty.Key, serializierContext));
                 }
             }
 
@@ -1388,8 +1404,23 @@ public virtual object CreateUntypedPropertyValue(IEdmStructuralProperty structur
             // 1) If we can get EdmType from model, Let's use it.
             // 2) If no (aka, we don't have an Edm type associated). So, let's treat it a Untyped.
             actualType = writeContext.GetEdmType(propertyValue, propertyType, true);
+
             if (actualType.IsStructuredOrUntyped())
             {
+                if (TypeHelper.IsEnum(propertyType))
+                {
+                    // we don't have the Edm enum type in the model, let's write it as string.
+                    return new ODataProperty
+                    {
+                        Name = structuralProperty.Name,
+
+                        // Shall we write the un-declared enum value as full-name string?
+                        // So, "Data":"Apple"  => should be ""Data":"Namespace.EnumTypeName.Apple" ?
+                        // We keep it simple to write it as string (enum member name), not the full-name string.
+                        Value = propertyValue.ToString()
+                    };
+                }
+
                 return propertyValue;
             }
 

test/Microsoft.AspNetCore.OData.E2E.Tests/Untyped/UntypedDataSource.cs

@@ -98,6 +98,20 @@ public static IList<InModelPerson> GetAllPeople()
                         }
                     },
 
+                    // not in model enum
+                    new InModelPerson
+                    {
+                        Id = 22, // special Id number
+                        Name = "Yin",
+                        Data = NotInModelEnum.Apple,
+                        Infos = new object[] { InModelColor.Blue, InModelColor.Green, NotInModelEnum.Apple },
+                        Containers = new Dictionary<string, object>
+                        {
+                            { "EnumDynamic1", InModelColor.Blue },
+                            { "EnumDynamic2", NotInModelEnum.Apple },
+                        }
+                    },
+
                     // In model complex
                     new InModelPerson
                     {

test/Microsoft.AspNetCore.OData.E2E.Tests/Untyped/UntypedTests.cs

@@ -324,6 +324,34 @@ public async Task QuerySinglePeople_OnDeclaredUntypedProperty(string request, st
             Assert.Equal(expected, payloadBody);
         }
 
+        [Fact]
+        public async Task QuerySinglePeople_WithDeclaredOrUndeclaredEnum_OnUntypedAndDynamicProperty()
+        {
+            // Arrange
+            HttpClient client = CreateClient();
+
+            // Act
+            HttpResponseMessage response = await client.GetAsync("odata/people/22");
+
+            // Assert
+            Assert.NotNull(response);
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.NotNull(response.Content);
+
+            string payloadBody = await response.Content.ReadAsStringAsync();
+
+            Assert.Equal("{\"@odata.context\":\"http://localhost/odata/$metadata#People/$entity\"," +
+                "\"Id\":22," +
+                "\"Name\":\"Yin\"," +
+                "\"[email protected]\":\"#Microsoft.AspNetCore.OData.E2E.Tests.Untyped.InModelColor\"," +
+                "\"EnumDynamic1\":\"Blue\"," +
+                "\"EnumDynamic2\":\"Apple\"," +
+                "\"[email protected]\":\"#String\"," +
+                "\"Data\":\"Apple\"," +
+                "\"Infos\":[\"Blue\",\"Green\",\"Apple\"]" +
+              "}", payloadBody);
+        }
+
         [Fact]
         public async Task QuerySinglePeople_WithCollectionInCollection_OnDeclaredUntypedProperty()
         {