Adds pure resolver for stitching (#4702)

src/HotChocolate/Core/src/Execution/Processing/MiddlewareContext.Pure.cs

@@ -66,7 +66,9 @@ public void Clear()
 
         public IObjectType ObjectType => _parentType;
 
-        public IFieldSelection Selection => _parentContext.Selection;
+        public IFieldSelection Selection => _selection;
+
+        public Path Path => _path;
 
         public IVariableValueCollection Variables => _parentContext.Variables;
 

src/HotChocolate/Core/src/Types/Resolvers/IPureResolverContext.cs

@@ -27,6 +27,11 @@ public interface IPureResolverContext : IHasContextData
     /// </summary>
     IObjectType ObjectType { get; }
 
+    /// <summary>
+    /// Gets the current execution path.
+    /// </summary>
+    Path Path { get; }
+
     /// <summary>
     /// Gets the field selection for which a field resolver is
     /// being executed.

src/HotChocolate/Core/src/Types/Resolvers/IResolverContext.cs

@@ -50,11 +50,6 @@ public interface IResolverContext : IPureResolverContext
     /// <value></value>
     NameString ResponseName { get; }
 
-    /// <summary>
-    /// Gets the current execution path.
-    /// </summary>
-    Path Path { get; }
-
     /// <summary>
     /// Indicates that the context has errors. To report new errors use <see cref="ReportError(IError)"/>
     /// </summary>

src/HotChocolate/Stitching/src/Stitching/Delegation/RemoteFieldHelper.cs

@@ -0,0 +1,29 @@
+using System.Collections.Generic;
+using HotChocolate.Resolvers;
+using HotChocolate.Types;
+
+namespace HotChocolate.Stitching.Delegation;
+
+internal static class RemoteFieldHelper
+{
+    public static object? RemoteFieldResolver(IPureResolverContext context)
+    {
+        if (!context.Selection.Field.Directives.Contains(DirectiveNames.Computed) &&
+            context.Parent<object>() is IReadOnlyDictionary<string, object> dict)
+        {
+            var responseName = context.Selection.SyntaxNode.Alias == null
+                ? context.Selection.SyntaxNode.Name.Value
+                : context.Selection.SyntaxNode.Alias.Value;
+
+            dict.TryGetValue(responseName, out var obj);
+            return DictionaryDeserializer.DeserializeResult(
+                context.Selection.Type,
+                obj,
+                context.Service<InputParser>(),
+                context.Path);
+        }
+
+        return null;
+    }
+}
+

src/HotChocolate/Stitching/src/Stitching/Utilities/StitchingTypeInterceptor.cs

@@ -62,18 +62,15 @@ public override void OnBeforeCompleteType(
             {
                 IReadOnlyDictionary<NameString, ISet<NameString>> externalFieldLookup =
                     completionContext.GetExternalFieldLookup();
-                if (externalFieldLookup.TryGetValue(
-                    objectType.Name,
-                    out ISet<NameString>? external))
+                if (externalFieldLookup.TryGetValue(objectType.Name, out ISet<NameString>? external))
                 {
                     foreach (ObjectFieldDefinition objectField in objectTypeDef.Fields)
                     {
                         if (external.Contains(objectField.Name) &&
                             _handledExternalFields.Add((objectTypeDef.Name, objectField.Name)))
                         {
-                            FieldMiddleware handleDictionary =
-                                FieldClassMiddlewareFactory.Create<DictionaryResultMiddleware>();
-                            objectField.MiddlewareDefinitions.Insert(0, new(handleDictionary));
+                            objectField.Resolvers = new FieldResolverDelegates(
+                                pureResolver: RemoteFieldHelper.RemoteFieldResolver);
                         }
                     }
                 }

src/HotChocolate/Stitching/test/Stitching.Tests/Integration/FederatedSchemaTests.cs

@@ -14,6 +14,10 @@
 using HotChocolate.Types;
 using Snapshooter.Xunit;
 using Xunit;
+using HotChocolate.Execution.Processing;
+using HotChocolate.Language;
+using HotChocolate.Utilities;
+using System.Linq;
 
 namespace HotChocolate.Stitching.Integration
 {
@@ -126,6 +130,54 @@ public async Task AutoMerge_AddLocal_Field_Execute()
             result.ToJson().MatchSnapshot();
         }
 
+        [Fact]
+        public async Task AutoMerge_CompileOperation()
+        {
+            // arrange
+            IHttpClientFactory httpClientFactory = CreateDefaultRemoteSchemas();
+
+            IRequestExecutor executor =
+                await new ServiceCollection()
+                    .AddSingleton(httpClientFactory)
+                    .AddGraphQL()
+                    .AddQueryType(d => d.Name("Query").Field("local").Resolve("I am local."))
+                    .AddRemoteSchema(_accounts)
+                    .AddRemoteSchema(_inventory)
+                    .AddRemoteSchema(_products)
+                    .AddRemoteSchema(_reviews)
+                    .BuildRequestExecutorAsync();
+
+            DocumentNode document = Utf8GraphQLParser.Parse(@"{
+                    me {
+                        id
+                        name
+                        reviews {
+                            body
+                            product {
+                                upc
+                            }
+                        }
+                    }
+                    local
+                }");
+
+            OperationDefinitionNode operationDefinition =
+                document.Definitions.OfType<OperationDefinitionNode>().Single();
+
+            // act
+            IPreparedOperation operation =
+                OperationCompiler.Compile(
+                    "a",
+                    document,
+                    operationDefinition,
+                    executor.Schema,
+                    executor.Schema.QueryType,
+                    new(new DefaultTypeConverter()));
+
+            // assert
+            operation.Print().MatchSnapshot();
+        }
+
         [Fact]
         public async Task Directive_Variables_Are_Correctly_Rewritten()
         {

src/HotChocolate/Stitching/test/Stitching.Tests/Integration/__snapshots__/FederatedSchemaTests.AutoMerge_CompileOperation.snap

@@ -0,0 +1,21 @@
+{
+  ... on Query {
+    me @__execute(id: 0, kind: DEFAULT, type: COMPOSITE) {
+      ... on User {
+        id @__execute(id: 2, kind: PURE, type: LEAF)
+        name @__execute(id: 3, kind: PURE, type: LEAF)
+        reviews @__execute(id: 4, kind: DEFAULT, type: COMPOSITE_LIST) {
+          ... on Review {
+            body @__execute(id: 5, kind: PURE, type: LEAF)
+            product @__execute(id: 6, kind: DEFAULT, type: COMPOSITE) {
+              ... on Product {
+                upc @__execute(id: 7, kind: PURE, type: LEAF)
+              }
+            }
+          }
+        }
+      }
+    }
+    local @__execute(id: 1, kind: DEFAULT, type: LEAF)
+  }
+}