Mutation Convention Type Inference Issue. (#6004)

* Added a test that shows an inssue in the type inference for mutation conventions.

* Fixed List Handling

* trailing ,

Author: michaelstaib

src/HotChocolate/Core/src/Types.Mutations/MutationConventionTypeInterceptor.cs

@@ -453,7 +453,7 @@ private void TryApplyPayloadConvention(
 
         var type = CreatePayloadType(
             payloadTypeName,
-            new(payloadFieldName, EnsureNullable(mutation.Type!)),
+            new(payloadFieldName, EnsureNullable(NormalizeTypeRef(mutation.Type!))),
             errorField);
         RegisterType(type);
 
@@ -826,7 +826,7 @@ private TypeReference EnsureNonNull(TypeReference typeRef)
         return Create(CreateTypeNode(new NonNullType(type)));
     }
 
-    private ITypeNode CreateTypeNode(IType type)
+    private static ITypeNode CreateTypeNode(IType type)
         => type switch
         {
             NonNullType nnt => new NonNullTypeNode((INullableTypeNode) CreateTypeNode(nnt.Type)),
@@ -835,41 +835,42 @@ private ITypeNode CreateTypeNode(IType type)
             _ => throw new NotSupportedException("Type is not supported.")
         };
 
-    private readonly ref struct Options
+    private static TypeReference NormalizeTypeRef(TypeReference typeRef)
     {
-        public Options(
-            string? inputTypeNamePattern,
-            string? inputArgumentName,
-            string? payloadTypeNamePattern,
-            string? payloadErrorTypeNamePattern,
-            string? payloadErrorsFieldName,
-            bool? apply)
+        if (typeRef is ExtendedTypeReference { Type.IsGeneric: true } extendedTypeRef &&
+            typeof(IMutationResult).IsAssignableFrom(extendedTypeRef.Type.Type))
         {
-            InputTypeNamePattern = inputTypeNamePattern ??
-                MutationConventionOptionDefaults.InputTypeNamePattern;
-            InputArgumentName = inputArgumentName ??
-                MutationConventionOptionDefaults.InputArgumentName;
-            PayloadTypeNamePattern = payloadTypeNamePattern ??
-                MutationConventionOptionDefaults.PayloadTypeNamePattern;
-            PayloadErrorsFieldName = payloadErrorsFieldName ??
-                MutationConventionOptionDefaults.PayloadErrorsFieldName;
-            PayloadErrorTypeNamePattern = payloadErrorTypeNamePattern ??
-                MutationConventionOptionDefaults.ErrorTypeNamePattern;
-            Apply = apply ??
-                MutationConventionOptionDefaults.ApplyToAllMutations;
+            return extendedTypeRef.WithType(extendedTypeRef.Type.TypeArguments[0]);
         }
 
-        public string InputTypeNamePattern { get; }
+        return typeRef;
+    }
+
+    private readonly ref struct Options(
+        string? inputTypeNamePattern,
+        string? inputArgumentName,
+        string? payloadTypeNamePattern,
+        string? payloadErrorTypeNamePattern,
+        string? payloadErrorsFieldName,
+        bool? apply)
+    {
+        public string InputTypeNamePattern { get; } = inputTypeNamePattern ??
+            MutationConventionOptionDefaults.InputTypeNamePattern;
 
-        public string InputArgumentName { get; }
+        public string InputArgumentName { get; } = inputArgumentName ??
+            MutationConventionOptionDefaults.InputArgumentName;
 
-        public string PayloadTypeNamePattern { get; }
+        public string PayloadTypeNamePattern { get; } = payloadTypeNamePattern ??
+            MutationConventionOptionDefaults.PayloadTypeNamePattern;
 
-        public string PayloadErrorTypeNamePattern { get; }
+        public string PayloadErrorTypeNamePattern { get; } = payloadErrorTypeNamePattern ??
+            MutationConventionOptionDefaults.ErrorTypeNamePattern;
 
-        public string PayloadErrorsFieldName { get; }
+        public string PayloadErrorsFieldName { get; } = payloadErrorsFieldName ??
+            MutationConventionOptionDefaults.PayloadErrorsFieldName;
 
-        public bool Apply { get; }
+        public bool Apply { get; } = apply ??
+            MutationConventionOptionDefaults.ApplyToAllMutations;
 
         public string FormatInputTypeName(string mutationName)
             => InputTypeNamePattern.Replace(

src/HotChocolate/Core/src/Types.Mutations/MutationResultTypeDiscoveryHandler.cs

@@ -4,9 +4,6 @@ namespace HotChocolate.Types;
 
 internal sealed class MutationResultTypeDiscoveryHandler(ITypeInspector typeInspector) : TypeDiscoveryHandler
 {
-    private readonly ITypeInspector _typeInspector = typeInspector ?? 
-        throw new ArgumentNullException(nameof(typeInspector));
-
     public override bool TryInferType(
         TypeReference typeReference,
         TypeDiscoveryInfo typeInfo,
@@ -18,15 +15,15 @@ public override bool TryInferType(
             typeof(IMutationResult).IsAssignableFrom(runtimeType) &&
             typeReference is ExtendedTypeReference typeRef)
         {
-            var type = _typeInspector.GetType(runtimeType.GenericTypeArguments[0]);
+            var type = GetNamedType(typeInspector.GetType(runtimeType.GenericTypeArguments[0]));
             schemaTypeRefs = new TypeReference[runtimeType.GenericTypeArguments.Length];
             schemaTypeRefs[0] = typeRef.WithType(type);
 
             for (var i = 1; i < runtimeType.GenericTypeArguments.Length; i++)
             {
                 var errorType = runtimeType.GenericTypeArguments[i];
 
-                type = _typeInspector.GetType(
+                type = typeInspector.GetType(
                     typeof(Exception).IsAssignableFrom(errorType)
                         ? typeof(ExceptionObjectType<>).MakeGenericType(errorType)
                         : typeof(ErrorObjectType<>).MakeGenericType(errorType));
@@ -40,4 +37,10 @@ public override bool TryInferType(
         schemaTypeRefs = null;
         return false;
     }
+
+    private IExtendedType GetNamedType(IExtendedType extendedType)
+    {
+        var typeInfo = typeInspector.CreateTypeInfo(extendedType);
+        return typeInspector.GetType(typeInfo.NamedType);
+    }
 }

src/HotChocolate/Core/test/Types.Mutations.Tests/AnnotationBasedMutations.cs

@@ -1114,6 +1114,20 @@ public async Task Query_Filed_Stays_NonNull()
         schema.MatchSnapshot();
     }
 
+    [Fact]
+    public async Task List_Return_Type()
+    {
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQL()
+                .AddQueryType(d => d.Field("abc").Resolve("def"))
+                .AddMutationType<ListReturnMutation>()
+                .AddMutationConventions()
+                .BuildSchemaAsync();
+
+        schema.MatchSnapshot();
+    }
+
     [Fact]
     public async Task Mutation_Aggregate_Error_Not_Mapped()
     {
@@ -1641,6 +1655,27 @@ public string DoSomething(string something)
 
     public record DoSomething2Payload(int? UserId);
 
+    public class ListReturnMutation
+    {
+        public MutationResult<List<ResultItem>> AddItem(AddItemInput input)
+            => new List<ResultItem>
+            {
+                new(),
+                new(),
+                new(),
+            };
+
+        public class AddItemInput
+        {
+            public int Count { get; set; }
+        }
+
+        public class ResultItem
+        {
+            public string Name { get; set; } = "Test";
+        }
+    }
+
     public record SomeNewError(string Message);
 
     public class CustomErrorConfig : MutationErrorConfiguration

src/HotChocolate/Core/test/Types.Mutations.Tests/__snapshots__/AnnotationBasedMutations.List_Return_Type.graphql

@@ -0,0 +1,24 @@
+schema {
+  query: Query
+  mutation: ListReturnMutation
+}
+
+type AddItemPayload {
+  resultItem: [ResultItem!]
+}
+
+type ListReturnMutation {
+  addItem(input: AddItemInput!): AddItemPayload!
+}
+
+type Query {
+  abc: String
+}
+
+type ResultItem {
+  name: String!
+}
+
+input AddItemInput {
+  count: Int!
+}