[Backport 8.0] Fix MultiGet response deserialization for non-matched IDs

.github/workflows/integration-jobs.yml

@@ -27,7 +27,8 @@ jobs:
           '8.3.3',
           '8.4.3',
           "8.5.3",
-          '8.6.0-SNAPSHOT',
+          '8.6.1',
+          "8.7.0-SNAPSHOT"
           'latest-8'
         ]
 

src/Elastic.Clients.Elasticsearch/Serialization/ResponseItemConverterFactory.cs

@@ -40,32 +40,32 @@ private sealed class ResponseItemConverter<TDocument> : JsonConverter<MultiGetRe
 
 			try
 			{
-				var result = JsonSerializer.Deserialize<GetResult<TDocument>>(ref readerCopy, options);
+				var result = JsonSerializer.Deserialize<MultiGetError>(ref reader, options);
 
-				// If we have a version number, we can be sure this isn't an error
-				if (result is not null && result.Version is not null)
+				if (result is not null && result.Error is not null)
 				{
-					reader = readerCopy; // Ensure we swap the reader to reflect the data we have consumed.
 					return new MultiGetResponseItem<TDocument>(result);
 				}
 			}
 			catch (Exception ex)
 			{
-				getResultException = ex;
+				errorException = ex;
 			}
 
 			try
 			{
-				var result = JsonSerializer.Deserialize<MultiGetError>(ref reader, options);
+				var result = JsonSerializer.Deserialize<GetResult<TDocument>>(ref readerCopy, options);
 
-				if (result is not null && result.Error is not null)
+				// If we have a version number, we can be sure this isn't an error
+				if (result is not null)
 				{
+					reader = readerCopy; // Ensure we swap the reader to reflect the data we have consumed.
 					return new MultiGetResponseItem<TDocument>(result);
 				}
 			}
 			catch (Exception ex)
 			{
-				errorException = ex;
+				getResultException = ex;
 			}
 
 			Exception innerException = null;

tests/Tests/Document/Multiple/MGet/MGetResponseSerialization.cs

@@ -0,0 +1,63 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information.
+
+using System.Linq;
+using Tests.Serialization;
+using Xunit;
+
+namespace Tests.Document.Multiple.MGet;
+
+public class MGetResponseSerialization : SerializerTestBase
+{
+	private const string ResponseJson = @"{
+    ""docs"": [
+		{
+			""_index"": ""foos"",
+			""_id"": ""001"",
+			""_version"": 5,
+			""_seq_no"": 8,
+			""_primary_term"": 1,
+			""found"": true,
+			""_source"": {
+				""id"": ""001"",
+				""name"": ""FooA""
+			}
+		}, 
+		{
+			""_index"": ""foos"",
+			""_id"": ""002"",
+			""_version"": 5,
+			""_seq_no"": 9,
+			""_primary_term"": 1,
+			""found"": true,
+			""_source"": {
+				""id"": ""002"",
+				""name"": ""FooB""
+			}
+		}, 
+		{
+			""_index"": ""foos"",
+			""_id"": ""nonexistant"",
+			""found"": false
+		}
+	]
+}";
+
+	[U]
+	public void MultiGetResponse_DeserializesCorrectly_WhenIdsAreNotFound()
+	{
+		var response = DeserializeJsonString<MultiGetResponse<Foo>>(ResponseJson);
+
+		response.Docs.Should().HaveCount(3);
+		response.Docs.ElementAt(0).Match(r => r.Found.Should().BeTrue(), _ => Assert.Fail("Union item should not have matched."));
+		response.Docs.ElementAt(1).Match(r => r.Found.Should().BeTrue(), _ => Assert.Fail("Union item should not have matched."));
+		response.Docs.ElementAt(2).Match(r => r.Found.Should().BeFalse(), _ => Assert.Fail("Union item should not have matched."));
+	}
+}
+
+internal class Foo
+{
+	public string Id { get; set; }
+	public string Name { get; set; }
+}