Handle StartObject or StartArray when reading QueryContainer collection (#4322)

This commit implements ReadJson for QueryContainerCollectionJsonConverter, to allow
handling a single query within a JSON object, or multiple queries within a JSON array.

Fixes #4311

Co-authored-by: Stuart Cam <[email protected]>

Author: russcam

src/Nest/QueryDsl/Abstractions/Container/QueryContainerJsonConverter.cs

@@ -40,9 +40,6 @@ protected override void SerializeJson(JsonWriter writer, object value, IQueryCon
 
 	internal class QueryContainerCollectionJsonConverter : JsonConverter
 	{
-		public override bool CanRead => false;
-		public override bool CanWrite => true;
-
 		public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
 		{
 			var collection = (IEnumerable<QueryContainer>)value;
@@ -62,8 +59,26 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
 			writer.WriteEndArray();
 		}
 
-		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) =>
-			throw new NotSupportedException();
+		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+		{
+			switch (reader.TokenType)
+			{
+				case JsonToken.StartObject:
+					return new[] { serializer.Deserialize<QueryContainer>(reader) };
+				case JsonToken.StartArray:
+					var queryContainers = new List<QueryContainer>();
+					while (reader.Read())
+					{
+						if (reader.TokenType == JsonToken.EndArray)
+							break;
+
+						queryContainers.Add(serializer.Deserialize<QueryContainer>(reader));
+					}
+					return queryContainers;
+				default:
+					return null;
+			}
+		}
 
 		public override bool CanConvert(Type objectType) => true;
 	}

src/Tests/Tests.Reproduce/GitHubIssue4311.cs

@@ -0,0 +1,99 @@
+using System;
+using System.Text;
+using Elastic.Xunit.XunitPlumbing;
+using Elasticsearch.Net;
+using FluentAssertions;
+using Nest;
+
+namespace Tests.Reproduce
+{
+	public class GithubIssue4311
+	{
+		[U]
+		public void CanDeserializeIndexResponseWithSingleFilterItem()
+		{
+			var json = @"{
+						  "".es-test-repro"": {
+									""aliases"": {
+										"".es-test-repro-alias1"": {
+											""filter"": {
+												""bool"": {
+													""must_not"": {
+														""exists"": {
+															""field"": ""field1""
+														}
+													}
+												}
+											}
+										}
+									},
+									""mappings"": {
+										""user"": {
+											""properties"": {
+												""email"": {
+													""type"": ""text"",
+													""fields"": {
+														""keyword"": {
+															""type"": ""keyword"",
+															""ignore_above"": 256
+														}
+													}
+												},
+												""firstName"": {
+													""type"": ""text"",
+													""fields"": {
+														""keyword"": {
+															""type"": ""keyword"",
+															""ignore_above"": 256
+														}
+													}
+												},
+												""isActive"": {
+													""type"": ""boolean""
+												},
+												""lastName"": {
+													""type"": ""text"",
+													""fields"": {
+														""keyword"": {
+															""type"": ""keyword"",
+															""ignore_above"": 256
+														}
+													}
+												},
+												""state"": {
+													""type"": ""text"",
+													""fields"": {
+														""keyword"": {
+															""type"": ""keyword"",
+															""ignore_above"": 256
+														}
+													}
+												}
+											}
+										}
+									},
+									""settings"": {
+										""index"": {
+											""creation_date"": ""1579594498360"",
+											""number_of_shards"": ""5"",
+											""number_of_replicas"": ""1"",
+											""uuid"": ""wqYY9c4xSH6nyilffGobmw"",
+											""version"": {
+												""created"": ""6080399""
+											},
+											""provided_name"": "".es-test-repro""
+										}
+									}
+								}
+							}";
+
+			var bytes = Encoding.UTF8.GetBytes(json);
+			var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
+			var connectionSettings = new ConnectionSettings(pool, new InMemoryConnection(bytes));
+			var client = new ElasticClient(connectionSettings);
+
+			var indexResponse = client.GetIndex(".es-test-repro");
+			indexResponse.IsValid.Should().BeTrue();
+		}
+	}
+}