search base types for unregistered types

When trying to determine the resource type name for a type "A" that is
not registered but is derived from another type "B" that is, then the
model manager should return the resource type name for type "B". This is
particularly useful when trying to serialize Entity Framework proxies.

Author: Chris Santero

JSONAPI.Tests/Core/ModelManagerTests.cs

@@ -25,6 +25,11 @@ private class CustomIdModel
             public string Data { get; set; }
         }
 
+        private class DerivedPost : Post
+        {
+            
+        }
+
         [TestMethod]
         public void FindsIdNamedId()
         {
@@ -90,6 +95,21 @@ public void GetResourceTypeName_returns_correct_value_for_registered_types()
             Assert.AreEqual("user-groups", userGroupsKey);
         }
 
+        [TestMethod]
+        public void GetResourceTypeNameForType_gets_name_for_closest_registered_base_type_for_unregistered_type()
+        {
+            // Arrange
+            var pluralizationService = new PluralizationService();
+            var mm = new ModelManager(pluralizationService);
+            mm.RegisterResourceType(typeof(Post));
+
+            // Act
+            var resourceTypeName = mm.GetResourceTypeNameForType(typeof(DerivedPost));
+
+            // Assert
+            resourceTypeName.Should().Be("posts");
+        }
+
         [TestMethod]
         public void GetResourceTypeNameForType_fails_when_getting_unregistered_type()
         {

JSONAPI/Core/ModelManager.cs

@@ -136,8 +136,15 @@ public string GetResourceTypeNameForType(Type type)
             if (IsSerializedAsMany(type))
                 type = GetElementType(type);
 
-            string resourceTypeName;
-            if (_resourceTypeNamesByType.Value.TryGetValue(type, out resourceTypeName)) return resourceTypeName;
+            var currentType = type;
+            while (currentType != null && currentType != typeof(Object))
+            {
+                string resourceTypeName;
+                if (_resourceTypeNamesByType.Value.TryGetValue(currentType, out resourceTypeName)) return resourceTypeName;
+
+                // This particular type wasn't registered, but maybe the base type was
+                currentType = currentType.BaseType;
+            }
 
             throw new InvalidOperationException(String.Format("The type `{0}` was not registered.", type.FullName));
         }