Extract error path from context.

src/HotChocolate/Core/src/Execution/Processing/PathHelper.cs

@@ -1,12 +1,13 @@
 using System;
 using System.Buffers;
+using System.Text.Json;
 
 namespace HotChocolate.Execution.Processing;
 
 internal static class PathHelper
 {
-    private const int _initialPathLength = 64; 
-    
+    private const int _initialPathLength = 64;
+
     public static Path CreatePathFromContext(ObjectResult parent)
         => CreatePath(parent);
 
@@ -18,6 +19,23 @@ public static Path CreatePathFromContext(ISelection selection, ResultData parent
             _ => throw new NotSupportedException($"{parent.GetType().FullName} is not a supported parent type."),
         };
 
+    public static Path CombinePath(ObjectResult parent, JsonElement errorSubPath, int skipSubElements)
+    {
+        var path = parent.Parent is null ? Path.Root : CreatePath(parent);
+
+        for (var i = skipSubElements; i < errorSubPath.GetArrayLength(); i++)
+        {
+            path = errorSubPath[i] switch
+            {
+                { ValueKind: JsonValueKind.String, } nameElement => path.Append(nameElement.GetString()!),
+                { ValueKind: JsonValueKind.Number, } indexElement => path.Append(indexElement.GetInt32()),
+                _ => throw new InvalidOperationException("The error path contains an unsupported element.")
+            };
+        }
+
+        return path;
+    }
+
     private static Path CreatePath(ResultData parent, object segmentValue)
     {
         var segments = ArrayPool<object>.Shared.Rent(_initialPathLength);

src/HotChocolate/Fusion/src/Core/Execution/ExecutionState.cs

@@ -41,11 +41,15 @@ public ExecutionState(
 
     /// <summary>
     /// Gets the selection set data that was collected during execution.
+    /// The selection set data represents the data that we have collected
+    /// from the subgraphs for the <see cref="SelectionSet"/>.
     /// </summary>
     public SelectionData[] SelectionSetData { get; }
 
     /// <summary>
     /// Gets the completed selection set result.
+    /// The selection set result represents the data for the
+    /// <see cref="SelectionSet"/> that we deliver to the user.
     /// </summary>
     public ObjectResult SelectionSetResult { get; }
 

src/HotChocolate/Fusion/src/Core/Execution/ExecutorUtils.cs

@@ -483,6 +483,8 @@ public static void TryInitializeExecutionState(QueryPlan queryPlan, ExecutionSta
     public static void ExtractErrors(
         ResultBuilder resultBuilder,
         JsonElement errors,
+        ObjectResult selectionSetResult,
+        int pathDepth,
         bool addDebugInfo)
     {
         if (errors.ValueKind is not JsonValueKind.Array)
@@ -492,13 +494,15 @@ public static void ExtractErrors(
 
         foreach (var error in errors.EnumerateArray())
         {
-            ExtractError(resultBuilder, error, addDebugInfo);
+            ExtractError(resultBuilder, error, selectionSetResult, pathDepth, addDebugInfo);
         }
     }
 
     private static void ExtractError(
         ResultBuilder resultBuilder,
         JsonElement error,
+        ObjectResult selectionSetResult,
+        int pathDepth,
         bool addDebugInfo)
     {
         if (error.ValueKind is not JsonValueKind.Object)
@@ -530,7 +534,9 @@ private static void ExtractError(
             if (error.TryGetProperty("path", out var remotePath) &&
                 remotePath.ValueKind is JsonValueKind.Array)
             {
-                // TODO : rewrite remote path if possible!
+                var path = PathHelper.CombinePath(selectionSetResult, remotePath, pathDepth);
+                errorBuilder.SetPath(path);
+
                 if (addDebugInfo)
                 {
                     errorBuilder.SetExtension("remotePath", remotePath);

src/HotChocolate/Fusion/src/Core/Execution/Nodes/Resolve.cs

@@ -17,7 +17,6 @@ namespace HotChocolate.Fusion.Execution.Nodes;
 /// </param>
 internal sealed class Resolve(int id, Config config) : ResolverNodeBase(id, config)
 {
-
     /// <summary>
     /// Gets the kind of this node.
     /// </summary>
@@ -69,7 +68,7 @@ protected override async Task OnExecuteAsync(
                 ProcessResponses(context, executionState, requests, responses, SubgraphName);
             }
         }
-        catch(Exception ex)
+        catch (Exception ex)
         {
             var error = context.OperationContext.ErrorHandler.CreateUnexpectedError(ex);
             context.Result.AddError(error.Build());
@@ -129,20 +128,22 @@ private void ProcessResponses(
         ref var request = ref MemoryMarshal.GetArrayDataReference(requests);
         ref var response = ref MemoryMarshal.GetArrayDataReference(responses);
         ref var end = ref Unsafe.Add(ref state, executionStates.Count);
+        var pathLength = Path.Length;
 
         while (Unsafe.IsAddressLessThan(ref state, ref end))
         {
             var data = UnwrapResult(response);
             var selectionSet = state.SelectionSet;
-            var selectionResults = state.SelectionSetData;
+            var selectionSetData = state.SelectionSetData;
+            var selectionSetResult = state.SelectionSetResult;
             var exportKeys = state.Requires;
             var variableValues = state.VariableValues;
 
-            ExtractErrors(context.Result, response.Errors, context.ShowDebugInfo);
+            ExtractErrors(context.Result, response.Errors, selectionSetResult, pathLength, context.ShowDebugInfo);
 
             // we extract the selection data from the request and add it to the
             // workItem results.
-            ExtractSelectionResults(SelectionSet, subgraphName, data, selectionResults);
+            ExtractSelectionResults(SelectionSet, subgraphName, data, selectionSetData);
 
             // next we need to extract any variables that we need for followup requests.
             ExtractVariables(data, context.QueryPlan, selectionSet, exportKeys, variableValues);
@@ -152,4 +153,4 @@ private void ProcessResponses(
             response = ref Unsafe.Add(ref response, 1)!;
         }
     }
-}
+}

src/HotChocolate/Fusion/src/Core/Execution/Nodes/ResolveByKeyBatch.cs

@@ -2,6 +2,7 @@
 using System.Runtime.InteropServices;
 using System.Text;
 using System.Text.Json;
+using HotChocolate.Execution.Processing;
 using HotChocolate.Fusion.Clients;
 using HotChocolate.Language;
 using static HotChocolate.Fusion.Execution.ExecutorUtils;
@@ -87,7 +88,7 @@ protected override async Task OnExecuteAsync(
                 ProcessResult(context, response, batchExecutionState);
             }
         }
-        catch(Exception ex)
+        catch (Exception ex)
         {
             var error = context.OperationContext.ErrorHandler.CreateUnexpectedError(ex);
             context.Result.AddError(error.Build());
@@ -134,17 +135,28 @@ private void ProcessResult(
         GraphQLResponse response,
         BatchExecutionState[] batchExecutionState)
     {
-        ExtractErrors(context.Result, response.Errors, context.ShowDebugInfo);
         var result = UnwrapResult(response, Requires);
-
         ref var batchState = ref MemoryMarshal.GetArrayDataReference(batchExecutionState);
         ref var end = ref Unsafe.Add(ref batchState, batchExecutionState.Length);
+        var pathLength = Path.Length;
+        var first = true;
 
         while (Unsafe.IsAddressLessThan(ref batchState, ref end))
         {
             if (result.TryGetValue(batchState.Key, out var data))
             {
-                ExtractSelectionResults(SelectionSet, SubgraphName, data, batchState.SelectionResults);
+                if (first)
+                {
+                    ExtractErrors(
+                        context.Result,
+                        response.Errors,
+                        batchState.SelectionSetResult,
+                        pathLength,
+                        context.ShowDebugInfo);
+                    first = false;
+                }
+
+                ExtractSelectionResults(SelectionSet, SubgraphName, data, batchState.SelectionSetData);
                 ExtractVariables(data, context.QueryPlan, SelectionSet, batchState.Requires, batchState.VariableValues);
             }
 
@@ -237,6 +249,7 @@ private Dictionary<string, JsonElement> UnwrapResult(
         if (exportKeys.Count == 1)
         {
             var key = exportKeys[0];
+
             foreach (var element in data.EnumerateArray())
             {
                 if (element.TryGetProperty(key, out var keyValue))
@@ -391,8 +404,17 @@ private readonly struct BatchExecutionState(string batchKey, ExecutionState exec
         public IReadOnlyList<string> Requires { get; } = executionState.Requires;
 
         /// <summary>
-        /// Gets the selection set data.
+        /// Gets the completed selection set result.
+        /// The selection set result represents the data for the
+        /// <see cref="ExecutionState.SelectionSet"/> that we deliver to the user.
+        /// </summary>
+        public ObjectResult SelectionSetResult { get; } = executionState.SelectionSetResult;
+
+        /// <summary>
+        /// Gets the selection set data that was collected during execution.
+        /// The selection set data represents the data that we have collected
+        /// from the subgraphs for the <see cref="ExecutionState.SelectionSet"/>.
         /// </summary>
-        public SelectionData[] SelectionResults { get; } = executionState.SelectionSetData;
+        public SelectionData[] SelectionSetData { get; } = executionState.SelectionSetData;
     }
-}
+}

src/HotChocolate/Fusion/test/Core.Tests/__snapshots__/ErrorTests.NestedResolveSubgraphError.snap

@@ -80,6 +80,11 @@ Result
           "column": 101
         }
       ],
+      "path": [
+        "reviewById",
+        "author",
+        "errorField"
+      ],
       "extensions": {
         "remotePath": [
           "userById",

src/HotChocolate/Fusion/test/Core.Tests/__snapshots__/ErrorTests.NestedResolveWithListSubgraphError.snap

@@ -80,6 +80,12 @@ Result
           "column": 84
         }
       ],
+      "path": [
+        "userById",
+        "reviews",
+        1,
+        "errorField"
+      ],
       "extensions": {
         "remotePath": [
           "userById",
@@ -96,6 +102,12 @@ Result
           "column": 84
         }
       ],
+      "path": [
+        "userById",
+        "reviews",
+        0,
+        "errorField"
+      ],
       "extensions": {
         "remotePath": [
           "userById",

src/HotChocolate/Fusion/test/Core.Tests/__snapshots__/ErrorTests.ResolveByKeySubgraphError.snap

@@ -80,6 +80,12 @@ Result
           "column": 94
         }
       ],
+      "path": [
+        "reviews",
+        0,
+        "author",
+        "errorField"
+      ],
       "extensions": {
         "remotePath": [
           "usersById",1,
@@ -95,6 +101,12 @@ Result
           "column": 94
         }
       ],
+      "path": [
+        "reviews",
+        0,
+        "author",
+        "errorField"
+      ],
       "extensions": {
         "remotePath": [
           "usersById",0,

src/HotChocolate/Fusion/test/Core.Tests/__snapshots__/ErrorTests.TopLevelResolveSubgraphError.snap

@@ -51,6 +51,9 @@ Result
           "column": 68
         }
       ],
+      "path": [
+        "errorField"
+      ],
       "extensions": {
         "remotePath": [
           "errorField"