[9.1] Fix deserialization of Context (#8688)

src/Elastic.Clients.Elasticsearch/_Generated/Types/Core/Context.Converters.g.cs

@@ -27,7 +27,7 @@ public sealed partial class ContextConverter : System.Text.Json.Serialization.Js
 {
 	public override Elastic.Clients.Elasticsearch.Core.Search.Context Read(ref System.Text.Json.Utf8JsonReader reader, System.Type typeToConvert, System.Text.Json.JsonSerializerOptions options)
 	{
-		var selector = static (ref System.Text.Json.Utf8JsonReader r, System.Text.Json.JsonSerializerOptions o) => JsonUnionSelector.ByPropertyOfT1(ref r, o, "dummy");
+		var selector = static (ref System.Text.Json.Utf8JsonReader r, System.Text.Json.JsonSerializerOptions o) => JsonUnionSelector.Match(ref r, o, static (ref System.Text.Json.Utf8JsonReader r, System.Text.Json.JsonSerializerOptions o) => JsonUnionSelector.MatchTokenTypes(ref r, o, Elastic.Clients.Elasticsearch.Serialization.JsonTokenTypes.StartObject | Elastic.Clients.Elasticsearch.Serialization.JsonTokenTypes.StartArray, static (ref System.Text.Json.Utf8JsonReader r, System.Text.Json.JsonSerializerOptions o) => JsonUnionSelector.T2(ref r, o)), static (ref System.Text.Json.Utf8JsonReader r, System.Text.Json.JsonSerializerOptions o) => JsonUnionSelector.T1(ref r, o));
 		return selector(ref reader, options) switch
 		{
 			Elastic.Clients.Elasticsearch.UnionTag.T1 => new Elastic.Clients.Elasticsearch.Core.Search.Context(reader.ReadValue<string>(options, null)),

src/Elastic.Clients.Elasticsearch/_Shared/Next/JsonReaderExtensions.cs

@@ -474,6 +474,9 @@ public static KeyValuePair<TKey, TValue> ReadKeyValuePairValue<TKey, TValue>(thi
 	public static List<T>? ReadSingleOrManyCollectionValue<T>(this ref Utf8JsonReader reader, JsonSerializerOptions options,
 		JsonReadFunc<T>? readElement)
 	{
+		// TODO: Allow passing a selector function to distinguish between single or many in complex scenarios
+		// (e.g. when the single element can be an array, see: GeoLocation).
+
 		if (reader.TokenType is JsonTokenType.Null)
 		{
 			return null;

src/Elastic.Clients.Elasticsearch/_Shared/Next/JsonUnionSelector.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Collections.Generic;
 using System.Text.Json;
 
 namespace Elastic.Clients.Elasticsearch.Serialization;
@@ -38,61 +37,146 @@ internal enum JsonTokenTypes
 
 internal static class JsonUnionSelector
 {
-	public static UnionTag ByTokenType(ref Utf8JsonReader reader, JsonSerializerOptions options, JsonTokenTypes first, JsonTokenTypes second)
+	/// <summary>
+	/// A selector function that always returns <see cref="UnionTag.None"/>.
+	/// </summary>
+	/// <param name="reader">A reference to the <see cref="Utf8JsonReader"/> instance.</param>
+	/// <param name="options">The <see cref="JsonSerializerOptions"/> to use.</param>
+	/// <returns>A static value of <see cref="UnionTag.None"/>.</returns>
+	public static UnionTag None(ref Utf8JsonReader reader, JsonSerializerOptions options)
+	{
+		_ = reader;
+		_ = options;
+		return UnionTag.None;
+	}
+
+	/// <summary>
+	/// A selector function that always returns <see cref="UnionTag.T1"/>.
+	/// </summary>
+	/// <param name="reader">A reference to the <see cref="Utf8JsonReader"/> instance.</param>
+	/// <param name="options">The <see cref="JsonSerializerOptions"/> to use.</param>
+	/// <returns>A static value of <see cref="UnionTag.T1"/>.</returns>
+	public static UnionTag T1(ref Utf8JsonReader reader, JsonSerializerOptions options)
 	{
 		_ = reader;
 		_ = options;
+		return UnionTag.T1;
+	}
 
-		if (((int)first & (1 << (int)reader.TokenType)) is not 0)
+	/// <summary>
+	/// A selector function that always returns <see cref="UnionTag.T2"/>.
+	/// </summary>
+	/// <param name="reader">A reference to the <see cref="Utf8JsonReader"/> instance.</param>
+	/// <param name="options">The <see cref="JsonSerializerOptions"/> to use.</param>
+	/// <returns>A static value of <see cref="UnionTag.T2"/>.</returns>
+	public static UnionTag T2(ref Utf8JsonReader reader, JsonSerializerOptions options)
+	{
+		_ = reader;
+		_ = options;
+		return UnionTag.T2;
+	}
+
+	// We avoid using a `params` array for performance reasons. Create `Match()` overloads with additional parameters as needed.
+	public static UnionTag Match(ref Utf8JsonReader reader, JsonSerializerOptions options, JsonUnionSelectorFunc case1, JsonUnionSelectorFunc case2)
+	{
+		if (case1(ref reader, options) is var tag1 and not UnionTag.None)
 		{
-			return UnionTag.T1;
+			return tag1;
 		}
 
-		if (((int)second & (1 << (int)reader.TokenType)) is not 0)
+		if (case2(ref reader, options) is var tag2 and not UnionTag.None)
 		{
-			return UnionTag.T2;
+			return tag2;
 		}
 
 		return UnionTag.None;
 	}
 
-	public static UnionTag ByPropertyOfT1(ref Utf8JsonReader reader, JsonSerializerOptions options, string name)
+	public static UnionTag MatchTokenTypes(ref Utf8JsonReader reader, JsonSerializerOptions options, JsonTokenTypes types, JsonUnionSelectorFunc next)
 	{
-		reader.ValidateToken(JsonTokenType.StartObject);
-
-		var internalReader = reader;
-
-		while (internalReader.Read() && (internalReader.TokenType is JsonTokenType.PropertyName))
+		if (((int)types & (1 << (int)reader.TokenType)) is not 0)
 		{
-			if (internalReader.ValueTextEquals(name))
-			{
-				return UnionTag.T1;
-			}
-
-			internalReader.Read();
-			internalReader.Skip();
+			return next(ref reader, options);
 		}
 
-		return UnionTag.T2;
+		return UnionTag.None;
 	}
 
-	public static UnionTag ByPropertyOfT2(ref Utf8JsonReader reader, JsonSerializerOptions options, string name)
+	public static UnionTag MatchProperty(ref Utf8JsonReader reader, JsonSerializerOptions options, string name, UnionTag result)
 	{
-		reader.ValidateToken(JsonTokenType.StartObject);
+		if (reader.TokenType is not JsonTokenType.StartObject)
+		{
+			return UnionTag.None;
+		}
 
 		var internalReader = reader;
 
 		while (internalReader.Read() && (internalReader.TokenType is JsonTokenType.PropertyName))
 		{
 			if (internalReader.ValueTextEquals(name))
 			{
-				return UnionTag.T2;
+				return result;
 			}
 
 			internalReader.Read();
 			internalReader.Skip();
 		}
 
-		return UnionTag.T1;
+		return UnionTag.None;
+	}
+
+	/// <summary>
+	/// A selector function that selects a union variant based on the current JSON token type.
+	/// </summary>
+	/// <param name="reader">A reference to the <see cref="Utf8JsonReader"/> instance.</param>
+	/// <param name="options">The <see cref="JsonSerializerOptions"/> to use.</param>
+	/// <param name="first">The JSON token types that resolve to <see cref="UnionTag.T1"/>.</param>
+	/// <param name="second">The JSON token types that resolve to <see cref="UnionTag.T2"/>.</param>
+	/// <returns>
+	/// Either <see cref="UnionTag.T1"/> or <see cref="UnionTag.T2"/> if the current token type of <paramref name="reader"/> matches one
+	/// of the provided JSON token types or <see cref="UnionTag.None"/>, if not.
+	/// </returns>
+	public static UnionTag ByTokenType(ref Utf8JsonReader reader, JsonSerializerOptions options, JsonTokenTypes first, JsonTokenTypes second)
+	{
+		return Match(ref reader, options,
+			(ref r, o) => MatchTokenTypes(ref r, o, first, T1),
+			(ref r, o) => MatchTokenTypes(ref r, o, second, T2)
+		);
+	}
+
+	/// <summary>
+	/// A selector function that selects a union variant based on the current JSON token type.
+	/// </summary>
+	/// <param name="reader">A reference to the <see cref="Utf8JsonReader"/> instance.</param>
+	/// <param name="options">The <see cref="JsonSerializerOptions"/> to use.</param>
+	/// <param name="name">The property name to look for.</param>
+	/// <returns>
+	/// <see cref="UnionTag.T1"/> if the <paramref name="reader"/> points to an object that contains a property of the given
+	/// <paramref name="name"/> or <see cref="UnionTag.T2"/>, if not.
+	/// </returns>
+	public static UnionTag ByPropertyOfT1(ref Utf8JsonReader reader, JsonSerializerOptions options, string name)
+	{
+		return Match(ref reader, options,
+			(ref r, o) => MatchProperty(ref r, o, name, UnionTag.T1),
+			T2
+		 );
+	}
+
+	/// <summary>
+	/// A selector function that selects a union variant based on the current JSON token type.
+	/// </summary>
+	/// <param name="reader">A reference to the <see cref="Utf8JsonReader"/> instance.</param>
+	/// <param name="options">The <see cref="JsonSerializerOptions"/> to use.</param>
+	/// <param name="name">The property name to look for.</param>
+	/// <returns>
+	/// <see cref="UnionTag.T2"/> if the <paramref name="reader"/> points to an object that contains a property of the given
+	/// <paramref name="name"/> or <see cref="UnionTag.T1"/>, if not.
+	/// </returns>
+	public static UnionTag ByPropertyOfT2(ref Utf8JsonReader reader, JsonSerializerOptions options, string name)
+	{
+		return Match(ref reader, options,
+			(ref r, o) => MatchProperty(ref r, o, name, UnionTag.T2),
+			T1
+		);
 	}
 }