[Fusion] Fix __typename not being properly selected (#8680)

Author: tobias-tengler

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Planning/OperationPlanner.cs

@@ -857,11 +857,13 @@ private void PlanNodeLookup(
         backlog = backlog.Push(unresolvable, current);
         backlog = backlog.Push(fieldsWithRequirements, stepId);
 
-        var selectionSetNode = resolvable
-            .WithSelections([
-                new FieldNode(IntrospectionFieldNames.TypeName),
-                ..resolvable.Selections
-            ]);
+        var resolvableSelections = resolvable.Selections;
+        if (!resolvableSelections.Any(IsTypeNameSelection))
+        {
+            resolvableSelections = [new FieldNode(IntrospectionFieldNames.TypeName), ..resolvableSelections];
+        }
+
+        var selectionSetNode = resolvable.WithSelections(resolvableSelections);
 
         var indexBuilder = index.ToBuilder();
         indexBuilder.Register(workItem.SelectionSet.Id, selectionSetNode);
@@ -956,11 +958,13 @@ private void PlanNode(
 
         (var sharedSelectionSet, var selectionSetsByType, index) = _selectionSetByTypePartitioner.Partition(input);
 
-        var nodeFieldSelectionSet =
-            new SelectionSetNode([
-                new FieldNode(IntrospectionFieldNames.TypeName),
-                ..sharedSelectionSet?.Selections ?? []
-            ]);
+        var sharedSelections = sharedSelectionSet?.Selections ?? [];
+        if (sharedSelections.Count < 1 || !sharedSelections.Any(IsTypeNameSelection))
+        {
+            sharedSelections = [new FieldNode(IntrospectionFieldNames.TypeName), ..sharedSelections];
+        }
+
+        var nodeFieldSelectionSet = new SelectionSetNode(sharedSelections);
         var nodeFieldWithSelectionSet = nodeField.WithSelectionSet(nodeFieldSelectionSet);
         var fallbackQuerySelectionSet = new SelectionSetNode([nodeFieldWithSelectionSet]);
 
@@ -1376,14 +1380,14 @@ private OperationDefinitionNode AddTypeNameToAbstractSelections(
         var rewriter = SyntaxRewriter.Create<Stack<ITypeDefinition>>(
             (node, path) =>
             {
-                if (node is not FieldNode fieldNode || fieldNode.SelectionSet is null)
+                if (node is not FieldNode { SelectionSet: {} selectionSet } fieldNode)
                 {
                     return node;
                 }
 
                 var type = path.Peek();
 
-                if (type.IsAbstractType())
+                if (type.IsAbstractType() && !selectionSet.Selections.Any(IsTypeNameSelection))
                 {
                     // we add the __typename field to all selection sets that have
                     // an abstract type context as we need the type context for
@@ -1393,8 +1397,9 @@ private OperationDefinitionNode AddTypeNameToAbstractSelections(
                     // required __typename and a runtime required type information.
                     var typenameNode = new FieldNode(IntrospectionFieldNames.TypeName)
                         .WithDirectives([new DirectiveNode("fusion__requirement")]);
+
                     return fieldNode.WithSelectionSet(new SelectionSetNode([
-                        typenameNode, ..fieldNode.SelectionSet.Selections
+                        typenameNode, ..selectionSet.Selections
                     ]));
                 }
 
@@ -1430,6 +1435,17 @@ private OperationDefinitionNode AddTypeNameToAbstractSelections(
         return (OperationDefinitionNode)rewriter.Rewrite(operation, context)!;
     }
 
+    private static bool IsTypeNameSelection(ISelectionNode selection)
+    {
+        if (selection is FieldNode field)
+        {
+            return field.Name.Value.Equals(IntrospectionFieldNames.TypeName)
+                && field.Alias is null;
+        }
+
+        return false;
+    }
+
     private readonly record struct PlanResult(
         OperationDefinitionNode InternalOperationDefinition,
         ImmutableList<PlanStep> Steps,

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Planning/Partitioners/SelectionSetPartitioner.cs

@@ -102,13 +102,22 @@ public SelectionSetPartitionerResult Partition(
 
         context.Nodes.Pop();
 
-        if (resolvableSelections is null && unresolvableSelections is null)
+        var isAbstractType = type.NamedType().IsAbstractType();
+
+        if (resolvableSelections is null && unresolvableSelections is null && !isAbstractType)
         {
             return (selectionSetNode, null);
         }
 
         if (unresolvableSelections is not null)
         {
+            if (isAbstractType && !unresolvableSelections.Any(IsTypeNameSelection))
+            {
+                unresolvableSelections = [
+                    new FieldNode(IntrospectionFieldNames.TypeName),
+                    ..unresolvableSelections];
+            }
+
             var unresolvableSelectionSet = new SelectionSetNode(unresolvableSelections);
             context.Register(selectionSetNode, unresolvableSelectionSet);
 
@@ -121,17 +130,19 @@ public SelectionSetPartitionerResult Partition(
             unresolvableSelections = null;
         }
 
-        var resolvableSelections2 = resolvableSelections ?? selectionSetNode.Selections;
+        resolvableSelections ??= [..selectionSetNode.Selections];
 
-        if (type.NamedType().IsAbstractType())
+        if (isAbstractType && !resolvableSelections.Any(IsTypeNameSelection))
         {
-            resolvableSelections2 = [new FieldNode(IntrospectionFieldNames.TypeName), ..resolvableSelections2];
+            resolvableSelections = [
+                new FieldNode(IntrospectionFieldNames.TypeName),
+                ..resolvableSelections];
         }
 
         var result =
         (
             Resolvable:
-                selectionSetNode.WithSelections(resolvableSelections2),
+                selectionSetNode.WithSelections(resolvableSelections),
             Unresolvable: unresolvableSelections is not null
                 ? selectionSetNode.WithSelections(unresolvableSelections)
                 : null
@@ -192,6 +203,17 @@ void CompleteSelection<T>(T original, T? resolvable, T? unresolvable, int index)
             // todo match correct inline fragment
             return providedSelectionSetNode;
         }
+
+        static bool IsTypeNameSelection(ISelectionNode selection)
+        {
+            if (selection is FieldNode field)
+            {
+                return field.Name.Value.Equals(IntrospectionFieldNames.TypeName)
+                    && field.Alias is null;
+            }
+
+            return false;
+        }
     }
 
     private (FieldNode?, FieldNode?) RewriteFieldNode(

src/HotChocolate/Fusion-vnext/test/Fusion.AspNetCore.Tests/AbstractTypeTests.cs

@@ -50,6 +50,47 @@ ... on Author {
         response.MatchSnapshot();
     }
 
+    [Fact]
+    public async Task Abstract_Type_Direct_Source_Schema_Call()
+    {
+        // arrange
+        using var server1 = CreateSourceSchema(
+            "A",
+            b => b
+                .AddQueryType<SourceSchema1.Query>()
+                .AddType<SourceSchema1.Discussion>());
+
+        // act
+        using var gateway = await CreateCompositeSchemaAsync(
+        [
+            ("A", server1)
+        ]);
+
+        // assert
+        using var client = GraphQLHttpClient.Create(gateway.CreateClient());
+
+        using var result = await client.PostAsync(
+            """
+            query {
+              interfaceConnection(first: 2) {
+                edges {
+                  node {
+                    id
+                  }
+                }
+                pageInfo {
+                  hasNextPage
+                }
+              }
+            }
+            """,
+            new Uri("http://localhost:5000/graphql"));
+
+        // act
+        using var response = await result.ReadAsResultAsync();
+        response.MatchSnapshot();
+    }
+
     [Fact]
     public async Task Abstract_Type_With_Concrete_Lookup()
     {
@@ -240,6 +281,10 @@ public class Query
 
             public List<SharedType> GetAbstractTypes() => [new Discussion(1), new Author(2), new Product(3)];
 
+            [UsePaging]
+            public IEnumerable<SharedType> InterfaceConnection()
+                => [new Discussion(1)];
+
             [Lookup]
             public Author GetAuthorById(int id) => new Author(id);
         }

src/HotChocolate/Fusion-vnext/test/Fusion.AspNetCore.Tests/__snapshots__/AbstractTypeTests.Abstract_Type_Direct_Source_Schema_Call.snap

@@ -0,0 +1,48 @@
+{
+  "data": {
+    "interfaceConnection": {
+      "edges": [
+        {
+          "node": {
+            "id": 1
+          }
+        }
+      ],
+      "pageInfo": {
+        "hasNextPage": false
+      }
+    }
+  },
+  "extensions": {
+    "fusion": {
+      "operationPlan": {
+        "id": "d16d3ad290a364c80b9616ef4cd80259628a504bddc7d1ef55a260758959adbe",
+        "operation": {
+          "kind": "Query",
+          "document": "{\n  interfaceConnection(first: 2) {\n    edges {\n      node {\n        __typename @fusion__requirement\n        id\n      }\n    }\n    pageInfo {\n      hasNextPage\n    }\n  }\n}",
+          "id": "45eb4c09cd33c661467dd26f8f97b5ad",
+          "hash": "45eb4c09cd33c661467dd26f8f97b5ad",
+          "shortHash": "45eb4c09"
+        },
+        "searchSpace": 1,
+        "nodes": [
+          {
+            "id": 1,
+            "type": "Operation",
+            "schema": "A",
+            "operation": {
+              "name": "Op_45eb4c09_1",
+              "kind": "Query",
+              "document": "query Op_45eb4c09_1 {\n  interfaceConnection(first: 2) {\n    edges {\n      node {\n        __typename\n        id\n      }\n    }\n    pageInfo {\n      hasNextPage\n    }\n  }\n}",
+              "hash": "ec5a97cdb5e116835c35d228dad9aa98e67468e436de260c0f03ae7d44044e78",
+              "shortHash": "ec5a97cd"
+            },
+            "responseNames": [
+              "interfaceConnection"
+            ]
+          }
+        ]
+      }
+    }
+  }
+}

src/HotChocolate/Fusion-vnext/test/Fusion.AspNetCore.Tests/__snapshots__/GlobalObjectIdentificationTests.Only_TypeName_Selected_On_Concrete_Type.snap

@@ -7,7 +7,7 @@
   "extensions": {
     "fusion": {
       "operationPlan": {
-        "id": "17f3bedec7fd1e8ea47f31347103804992c87b23a6005bde9286dcc52e88c060",
+        "id": "bcdc83b0403a3cc4a375d56494927687654063caf35a6fdfe03f6f4146b12b8a",
         "operation": {
           "kind": "Query",
           "document": "{\n  node(id: \"RGlzY3Vzc2lvbjox\") {\n    __typename @fusion__requirement\n    ... on Discussion {\n      __typename\n    }\n  }\n}",
@@ -51,9 +51,9 @@
             "operation": {
               "name": "Op_72167d7d_3",
               "kind": "Query",
-              "document": "query Op_72167d7d_3 {\n  node: discussionById(discussionId: \"RGlzY3Vzc2lvbjox\") {\n    __typename\n    __typename\n  }\n}",
-              "hash": "1a577bbb61a345b7eb4307da4f0a5fe835b9b58331bc96c0685594381b0c31df",
-              "shortHash": "1a577bbb"
+              "document": "query Op_72167d7d_3 {\n  node: discussionById(discussionId: \"RGlzY3Vzc2lvbjox\") {\n    __typename\n  }\n}",
+              "hash": "cf9d08901253a456552f6be60517863eba31e024544cf744d8139eb93355ac5b",
+              "shortHash": "cf9d0890"
             },
             "responseNames": [
               "node"

src/HotChocolate/Fusion-vnext/test/Fusion.Execution.Tests/Planning/__snapshots__/GlobalObjectIdentificationTests.Node_FIeld_Selections_On_Interface_And_Concrete_Type_Both_Have_Different_Dependencies.yaml

@@ -4,7 +4,6 @@ operation:
         $id: ID!
       ) {
         node(id: $id) {
-          __typename @fusion__requirement
           __typename
           id
           ... on ProductList {
@@ -41,7 +40,6 @@ nodes:
         $id: ID!
       ) {
         node(id: $id) {
-          __typename
           __typename
           id
         }
@@ -58,7 +56,6 @@ nodes:
         node(id: $id) {
           __typename
           ... on Item2 {
-            __typename
             __typename
             id
             products {
@@ -126,7 +123,6 @@ nodes:
         node(id: $id) {
           __typename
           ... on Item1 {
-            __typename
             __typename
             id
             products {

src/HotChocolate/Fusion-vnext/test/Fusion.Execution.Tests/Planning/__snapshots__/GlobalObjectIdentificationTests.Node_Field_Alongside_Regular_Root_Selections.yaml

@@ -7,7 +7,6 @@ operation:
           username
         }
         node(id: $id) {
-          __typename @fusion__requirement
           __typename
           ... on Discussion {
             title
@@ -33,7 +32,6 @@ nodes:
       ) {
         node(id: $id) {
           __typename
-          __typename
         }
       }
     dependencies:
@@ -48,7 +46,6 @@ nodes:
         node(id: $id) {
           __typename
           ... on Discussion {
-            __typename
             __typename
             title
           }

src/HotChocolate/Fusion-vnext/test/Fusion.Execution.Tests/Planning/__snapshots__/GlobalObjectIdentificationTests.Node_Field_Just_Id_And_Typename_Selected.yaml

@@ -4,9 +4,8 @@ operation:
         $id: ID!
       ) {
         node(id: $id) {
-          __typename @fusion__requirement
-          __typename
           id
+          __typename
         }
       }
     name: testQuery
@@ -26,7 +25,6 @@ nodes:
         $id: ID!
       ) {
         node(id: $id) {
-          __typename
           id
           __typename
         }

src/HotChocolate/Fusion-vnext/test/Fusion.Execution.Tests/Planning/__snapshots__/GlobalObjectIdentificationTests.Node_Field_Just_Typename_Selected.yaml

@@ -4,7 +4,6 @@ operation:
         $id: ID!
       ) {
         node(id: $id) {
-          __typename @fusion__requirement
           __typename
         }
       }
@@ -26,7 +25,6 @@ nodes:
       ) {
         node(id: $id) {
           __typename
-          __typename
         }
       }
     dependencies: