Fix #4956

src/StrawberryShake/Client/src/Core/Json/JsonExtensionParser.cs

@@ -0,0 +1,18 @@
+using System.Collections.Generic;
+using System.Text.Json;
+
+namespace StrawberryShake.Json;
+
+public static class JsonExtensionParser
+{
+    public static IReadOnlyDictionary<string, object?>? ParseExtensions(JsonElement result)
+    {
+        if (result is { ValueKind: JsonValueKind.Object })
+        {
+            var extensions = JsonSerializationHelper.ReadValue(result);
+            return (IReadOnlyDictionary<string, object?>?)extensions;
+        }
+
+        return null;
+    }
+}

src/StrawberryShake/Client/src/Core/OperationResultBuilder.cs

@@ -25,6 +25,7 @@ public IOperationResult<TResultData> Build(
         TResultData? data = null;
         IOperationResultDataInfo? dataInfo = null;
         IReadOnlyList<IClientError>? errors = null;
+        IReadOnlyDictionary<string, object?>? extensions = null;
 
         try
         {
@@ -42,6 +43,12 @@ public IOperationResult<TResultData> Build(
                 {
                     errors = JsonErrorParser.ParseErrors(errorsProp);
                 }
+
+                if (body.RootElement.TryGetProperty(ResultFields.Extensions, out var extensionsProp) &&
+                    extensionsProp.ValueKind is JsonValueKind.Object)
+                {
+                    extensions = JsonExtensionParser.ParseExtensions(extensionsProp);
+                }
             }
         }
         catch (Exception ex)
@@ -71,7 +78,7 @@ public IOperationResult<TResultData> Build(
             dataInfo,
             ResultDataFactory,
             errors,
-            response.Extensions,
+            extensions,
             response.ContextData);
     }
 

src/StrawberryShake/Client/src/Core/ResultFields.cs

@@ -7,4 +7,5 @@ public static class ResultFields
     public const string Path = "path";
     public const string Label = "label";
     public const string HasNext = "hasNext";
+    public const string Extensions = "extensions";
 }

src/StrawberryShake/Client/test/Core.Tests/OperationResultBuilderTests.cs

@@ -0,0 +1,86 @@
+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+
+namespace StrawberryShake;
+
+public class OperationResultBuilderTests
+{
+    [Fact]
+    public void Build_With_Extensions()
+    {
+        // arrange
+        var factory = new DocumentDataFactory();
+        var builder = new DocumentOperationResultBuilder(factory);
+
+        // According to the current design, all implementations of IConnection operate
+        // on JsonDocuments which are deserialized straight from response streams and
+        // very few properties in the Response object are in fact ever initialized,
+        // including Response.Extensions. It is therefore safe to assume that, at
+        // least for now, OperationResultBuilder is the best place to actually parse
+        // and extract "extensions".
+        var body = JsonDocument.Parse(@"{""data"": { }, ""extensions"": { ""a"": 1, ""b"": { ""c"": ""Strawberry"" }, ""d"": 3.14 } }");
+        var response = new Response<JsonDocument>(body, null);
+
+        // act
+
+        var result = builder.Build(response);
+
+        // assert
+        Assert.NotEmpty(result.Extensions);
+        Assert.Equal(1L, result.Extensions["a"]);
+
+        var b = (IReadOnlyDictionary<string, object?>?)result.Extensions["b"];
+
+        Assert.NotNull(b);
+        Assert.Equal("Strawberry", b["c"]);
+
+        Assert.Equal(3.14, result.Extensions["d"]);
+    }
+
+    internal class Document
+    {
+    }
+
+    internal class DocumentDataInfo : IOperationResultDataInfo
+    {
+        public IReadOnlyCollection<EntityId> EntityIds { get; } = ArraySegment<EntityId>.Empty;
+
+        public ulong Version { get; } = 0;
+
+        public IOperationResultDataInfo WithVersion(ulong version)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    internal class DocumentDataFactory : IOperationResultDataFactory<Document>
+    {
+        public Type ResultType { get => typeof(Document); }
+
+        public Document Create(IOperationResultDataInfo dataInfo, IEntityStoreSnapshot? snapshot = null)
+        {
+            return new Document();
+        }
+
+        object IOperationResultDataFactory.Create(IOperationResultDataInfo dataInfo, IEntityStoreSnapshot? snapshot)
+        {
+            return Create(dataInfo, snapshot);
+        }
+    }
+
+    internal class DocumentOperationResultBuilder : OperationResultBuilder<Document>
+    {
+        public DocumentOperationResultBuilder(IOperationResultDataFactory<Document> resultDataFactory)
+        {
+            ResultDataFactory = resultDataFactory;
+        }
+
+        protected override IOperationResultDataFactory<Document> ResultDataFactory { get; }
+
+        protected override IOperationResultDataInfo BuildData(JsonElement obj)
+        {
+            return new DocumentDataInfo();
+        }
+    }
+}