Deserialize sort short forms

This commit updates SortFormatter to be able
to deserialize sorts that specify only the field
name as a string, or only specify a sort order
value.

Fixes #4797

src/Nest/CommonOptions/Sorting/SortFormatter.cs

@@ -22,55 +22,82 @@ public ISort Deserialize(ref JsonReader reader, IJsonFormatterResolver formatter
 		{
 			ISort sort = null;
 
-			var count = 0;
-			while (reader.ReadIsInObject(ref count))
+			switch (reader.GetCurrentJsonToken())
 			{
-				var sortProperty = reader.ReadPropertyNameSegmentRaw();
-				if (SortFields.TryGetValue(sortProperty, out var value))
+				case JsonToken.String:
 				{
-					switch (value)
+					var sortProperty = reader.ReadString();
+					sort = new FieldSort { Field = sortProperty };
+					break;
+				}
+				case JsonToken.BeginObject:
+				{
+					var count = 0;
+					while (reader.ReadIsInObject(ref count))
 					{
-						case 0:
-							var propCount = 0;
-							string field = null;
-							var geoDistanceSegment = reader.ReadNextBlockSegment();
-							var geoDistanceReader = new JsonReader(geoDistanceSegment.Array, geoDistanceSegment.Offset);
-							IEnumerable<GeoLocation> points = null;
-							while (geoDistanceReader.ReadIsInObject(ref propCount))
+						var sortProperty = reader.ReadPropertyNameSegmentRaw();
+						if (SortFields.TryGetValue(sortProperty, out var value))
+						{
+							switch (value)
 							{
-								var nameSegment = geoDistanceReader.ReadPropertyNameSegmentRaw();
-								if (geoDistanceReader.GetCurrentJsonToken() == JsonToken.BeginArray)
-								{
-									field = nameSegment.Utf8String();
-									points = formatterResolver.GetFormatter<IEnumerable<GeoLocation>>()
+								case 0:
+									var propCount = 0;
+									string field = null;
+									var geoDistanceSegment = reader.ReadNextBlockSegment();
+									var geoDistanceReader = new JsonReader(geoDistanceSegment.Array, geoDistanceSegment.Offset);
+									IEnumerable<GeoLocation> points = null;
+									while (geoDistanceReader.ReadIsInObject(ref propCount))
+									{
+										var nameSegment = geoDistanceReader.ReadPropertyNameSegmentRaw();
+										if (geoDistanceReader.GetCurrentJsonToken() == JsonToken.BeginArray)
+										{
+											field = nameSegment.Utf8String();
+											points = formatterResolver.GetFormatter<IEnumerable<GeoLocation>>()
+												.Deserialize(ref geoDistanceReader, formatterResolver);
+											break;
+										}
+
+										// skip value if not array
+										geoDistanceReader.ReadNextBlock();
+									}
+									geoDistanceReader = new JsonReader(geoDistanceSegment.Array, geoDistanceSegment.Offset);
+									var geoDistanceSort = formatterResolver.GetFormatter<GeoDistanceSort>()
 										.Deserialize(ref geoDistanceReader, formatterResolver);
+									geoDistanceSort.Field = field;
+									geoDistanceSort.Points = points;
+									sort = geoDistanceSort;
 									break;
-								}
-
-								// skip value if not array
-								geoDistanceReader.ReadNextBlock();
+								case 1:
+									sort = formatterResolver.GetFormatter<ScriptSort>()
+										.Deserialize(ref reader, formatterResolver);
+									break;
+							}
+						}
+						else
+						{
+							var field = sortProperty.Utf8String();
+							FieldSort sortField;
+							if (reader.GetCurrentJsonToken() == JsonToken.String)
+							{
+								var sortOrder = formatterResolver.GetFormatter<SortOrder>()
+									.Deserialize(ref reader, formatterResolver);
+								sortField = new FieldSort { Field = field, Order = sortOrder };
 							}
-							geoDistanceReader = new JsonReader(geoDistanceSegment.Array, geoDistanceSegment.Offset);
-							var geoDistanceSort = formatterResolver.GetFormatter<GeoDistanceSort>()
-								.Deserialize(ref geoDistanceReader, formatterResolver);
-							geoDistanceSort.Field = field;
-							geoDistanceSort.Points = points;
-							sort = geoDistanceSort;
-							break;
-						case 1:
-							sort = formatterResolver.GetFormatter<ScriptSort>()
-								.Deserialize(ref reader, formatterResolver);
-							break;
+							else
+							{
+								sortField = formatterResolver.GetFormatter<FieldSort>()
+									.Deserialize(ref reader, formatterResolver);
+								sortField.Field = field;
+							}
+
+							sort = sortField;
+						}
 					}
+
+					break;
 				}
-				else
-				{
-					var field = sortProperty.Utf8String();
-					var sortField = formatterResolver.GetFormatter<FieldSort>()
-						.Deserialize(ref reader, formatterResolver);
-					sortField.Field = field;
-					sort = sortField;
-				}
+				default:
+					throw new JsonParsingException($"Cannot deserialize {nameof(ISort)} from {reader.GetCurrentJsonToken()}");
 			}
 
 			return sort;

tests/Tests.Reproduce/GitHubIssue4797.cs

@@ -0,0 +1,46 @@
+// 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.Text;
+using Elastic.Elasticsearch.Xunit.XunitPlumbing;
+using FluentAssertions;
+using Nest;
+using Tests.Core.Client;
+
+namespace Tests.Reproduce
+{
+	public class GitHubIssue4797
+	{
+		[U]
+		public void DeserializeSortWithOnlyFieldAndOrder()
+		{
+			var json = @"
+			{
+			    ""sort"" : [
+			        { ""post_date"" : {""order"" : ""asc""}},
+			        ""user"",
+			        { ""name"" : ""desc"" },
+			        { ""age"" : ""desc"" },
+			        ""_score""
+			    ],
+			    ""query"" : {
+			        ""term"" : { ""user"" : ""kimchy"" }
+			    }
+			}
+			";
+
+			var bytes = Encoding.UTF8.GetBytes(json);
+			var client = TestClient.FixedInMemoryClient(bytes);
+
+			using var stream = client.ConnectionSettings.MemoryStreamFactory.Create(bytes);
+			var request = client.RequestResponseSerializer.Deserialize<SearchRequest>(stream);
+
+			request.Should().NotBeNull();
+			request.Sort.Should().NotBeNull().And.HaveCount(5);
+			request.Sort[1].SortKey.Should().Be("user");
+			request.Sort[2].SortKey.Should().Be("name");
+			request.Sort[2].Order.Should().Be(SortOrder.Descending);
+		}
+	}
+}