Added support for generic object type extensions.

src/Core/Types.Tests/Types/EnumTypeTests.cs

@@ -489,6 +489,16 @@ public void Deprecate_Fields_With_Deprecated_Attribute()
             schema.ToString().MatchSnapshot();
         }
 
+        [Fact]
+        public void EnumType_That_Is_Bound_To_String_Should_Not_Interfere_With_Scalar()
+        {
+            SchemaBuilder.New()
+                .AddQueryType<SomeQueryType>()
+                .Create()
+                .ToString()
+                .MatchSnapshot();
+        }
+
         public enum Foo
         {
             Bar1,
@@ -511,5 +521,25 @@ public enum FooDeprecated
             [GraphQLDeprecated("Baz.")]
             Bar2
         }
+
+        public class SomeQueryType : ObjectType
+        {
+            protected override void Configure(IObjectTypeDescriptor descriptor)
+            {
+                descriptor.Name("Query");
+                descriptor.Field("a").Type<SomeEnumType>().Resolver("DEF");
+                descriptor.Field("b").Type<StringType>().Resolver("StringResolver");
+            }
+        }
+
+        public class SomeEnumType
+            : EnumType<string>
+        {
+            protected override void Configure(IEnumTypeDescriptor<string> descriptor)
+            {
+                descriptor.Name("Some");
+                descriptor.Value("ABC").Name("DEF");
+            }
+        }
     }
 }

src/Core/Types.Tests/Types/ObjectTypeExtensionTests.cs

@@ -29,6 +29,57 @@ public void ObjectTypeExtension_AddField()
             Assert.True(type.Fields.ContainsField("test"));
         }
 
+        [Fact]
+        public void ObjectTypeExtension_Infer_Field()
+        {
+            // arrange
+            // act
+            ISchema schema = SchemaBuilder.New()
+                .AddQueryType<FooType>()
+                .AddType<GenericFooTypeExtension>()
+                .Create();
+
+            // assert
+            ObjectType type = schema.GetType<ObjectType>("Foo");
+            Assert.True(type.Fields.ContainsField("test"));
+        }
+
+        [Fact]
+        public void ObjectTypeExtension_Declare_Field()
+        {
+            // arrange
+            // act
+            ISchema schema = SchemaBuilder.New()
+                .AddQueryType<FooType>()
+                .AddType(new ObjectTypeExtension<FooExtension>(d =>
+                {
+                    d.Name("Foo");
+                    d.Field(t => t.Test).Type<IntType>();
+                }))
+                .Create();
+
+            // assert
+            ObjectType type = schema.GetType<ObjectType>("Foo");
+            Assert.True(type.Fields.ContainsField("test"));
+            Assert.IsType<IntType>(type.Fields["test"].Type);
+        }
+
+        [Fact]
+        public async Task ObjectTypeExtension_Execute_Infer_Field()
+        {
+            // arrange
+            // act
+            IQueryExecutor executor = SchemaBuilder.New()
+                .AddQueryType<FooType>()
+                .AddType<GenericFooTypeExtension>()
+                .Create()
+                .MakeExecutable();
+
+            // assert
+            IExecutionResult result = await executor.ExecuteAsync("{ test }");
+            result.MatchSnapshot();
+        }
+
         [Fact]
         public void ObjectTypeExtension_OverrideResolver()
         {
@@ -124,7 +175,7 @@ public void ObjectTypeExtension_DeprecateField_Obsolete()
         }
 
         [Fact]
-        public void ObjectTypeExtension_DepricateField_With_Reason()
+        public void ObjectTypeExtension_DeprecateField_With_Reason()
         {
             // arrange
             FieldResolverDelegate resolver =
@@ -148,7 +199,7 @@ public void ObjectTypeExtension_DepricateField_With_Reason()
         }
 
         [Fact]
-        public void ObjectTypeExtension_DepricateField_Without_Reason()
+        public void ObjectTypeExtension_DeprecateField_Without_Reason()
         {
             // arrange
             FieldResolverDelegate resolver =
@@ -484,6 +535,16 @@ protected override void Configure(
             }
         }
 
+        public class GenericFooTypeExtension
+            : ObjectTypeExtension<FooExtension>
+        {
+            protected override void Configure(
+                IObjectTypeDescriptor<FooExtension> descriptor)
+            {
+                descriptor.Name("Foo");
+            }
+        }
+
         public class Foo
         {
             public string Description { get; } = "hello";
@@ -494,6 +555,11 @@ public string GetName(string a)
             }
         }
 
+        public class FooExtension
+        {
+            public string Test { get; set; } = "Test123";
+        }
+
         public class FooResolver
         {
             public string GetName2()

src/Core/Types.Tests/Types/__snapshots__/EnumTypeTests.EnumType_That_Is_Bound_To_String_Should_Not_Interfere_With_Scalar.snap

@@ -0,0 +1,15 @@
+schema {
+  query: Query
+}
+
+type Query {
+  a: Some
+  b: String
+}
+
+enum Some {
+  DEF
+}
+
+"The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text."
+scalar String

src/Core/Types.Tests/Types/__snapshots__/ObjectTypeExtensionTests.ObjectTypeExtension_Execute_Infer_Field.snap

@@ -0,0 +1,8 @@
+{
+  "Data": {
+    "test": "Test123"
+  },
+  "Extensions": {},
+  "Errors": [],
+  "ContextData": {}
+}

src/Core/Types/Types/Descriptors/Definitions/ObjectTypeDefinition.cs

@@ -1,4 +1,4 @@
-using System.Collections;
+using System;
 using System.Collections.Generic;
 using HotChocolate.Language;
 
@@ -7,13 +7,23 @@ namespace HotChocolate.Types.Descriptors.Definitions
     public class ObjectTypeDefinition
         : TypeDefinitionBase<ObjectTypeDefinitionNode>
     {
+        public override Type ClrType
+        {
+            get => base.ClrType;
+            set
+            {
+                base.ClrType = value;
+                FieldBindingType = value;
+            }
+        }
+
+        public Type FieldBindingType { get; set; }
+
         public IsOfType IsOfType { get; set; }
 
         public ICollection<ITypeReference> Interfaces { get; } =
             new List<ITypeReference>();
 
-        public BindingBehavior FieldBindingBehavior { get; set; }
-
         public IBindableList<ObjectFieldDefinition> Fields { get; } =
             new BindableList<ObjectFieldDefinition>();
 

src/Core/Types/Types/Descriptors/Definitions/TypeDefinitionBase~1.cs

@@ -17,7 +17,7 @@ protected TypeDefinitionBase() { }
         /// <summary>
         /// Gets or sets the .net type representation of this type.
         /// </summary>
-        public Type ClrType
+        public virtual Type ClrType
         {
             get => _clrType;
             set

src/Core/Types/Types/Descriptors/Helpers/FieldDescriptorUtilities.cs

@@ -41,10 +41,28 @@ public static void AddImplicitFields<TDescriptor, TMember, TField>(
             where TMember : MemberInfo
             where TField : FieldDefinitionBase
         {
-            if (descriptor.ClrType != typeof(object))
+            AddImplicitFields<TDescriptor, TMember, TField>(
+                descriptor,
+                descriptor.ClrType,
+                createdFieldDefinition,
+                fields,
+                handledMembers);
+        }
+
+        public static void AddImplicitFields<TDescriptor, TMember, TField>(
+            TDescriptor descriptor,
+            Type fieldBindingType,
+            Func<TMember, TField> createdFieldDefinition,
+            IDictionary<NameString, TField> fields,
+            ISet<TMember> handledMembers)
+            where TDescriptor : IHasDescriptorContext
+            where TMember : MemberInfo
+            where TField : FieldDefinitionBase
+        {
+            if (fieldBindingType != typeof(object))
             {
                 foreach (TMember member in descriptor.Context.Inspector
-                    .GetMembers(descriptor.ClrType)
+                    .GetMembers(fieldBindingType)
                     .OfType<TMember>())
                 {
                     TField fieldDefinition = createdFieldDefinition(member);

src/Core/Types/Types/Descriptors/InterfaceTypeDescriptor.cs

@@ -22,10 +22,8 @@ protected InterfaceTypeDescriptor(
             }
 
             Definition.ClrType = clrType;
-            Definition.Name =
-                context.Naming.GetTypeName(clrType, TypeKind.Interface);
-            Definition.Description =
-                context.Naming.GetTypeDescription(clrType, TypeKind.Interface);
+            Definition.Name = context.Naming.GetTypeName(clrType, TypeKind.Interface);
+            Definition.Description = context.Naming.GetTypeDescription(clrType, TypeKind.Interface);
         }
 
         protected InterfaceTypeDescriptor(

src/Core/Types/Types/Descriptors/ObjectTypeDescriptor.cs

@@ -309,6 +309,10 @@ public static ObjectTypeDescriptor<T> New<T>(
             IDescriptorContext context) =>
             new ObjectTypeDescriptor<T>(context);
 
+        public static ObjectTypeExtensionDescriptor<T> NewExtension<T>(
+            IDescriptorContext context) =>
+            new ObjectTypeExtensionDescriptor<T>(context);
+
         public static ObjectTypeDescriptor FromSchemaType(
             IDescriptorContext context,
             Type schemaType)