using System;

using System.Text.Json;

using System.Text.Json.Serialization;

​

public class Program

{

    public static void Main()

    {

        //this works

        var json = "{\"AuthorId\":\"6917d697c1ab4fb7b2978b2a23100bfc\",\"Title\":\"test title\"}";

        //this doesn't work

        //var json = "{\"AuthorId\":\"6917d697-c1ab-4fb7-b297-8b2a23100bfc\",\"Title\":\"test title\"}";

        var result1 = Newtonsoft.Json.JsonConvert.DeserializeObject<Post>(json);

        result1.Dump();

        var result2 = System.Text.Json.JsonSerializer.Deserialize<Post>(json);

        result2.Dump();

    }

}

​

public class GuidJsonConverter : JsonConverter<Guid>

{

    public override Guid Read(

            ref Utf8JsonReader reader,

            Type typeToConvert,

            JsonSerializerOptions options) =>

                Guid.Parse(reader.GetString()!);

​

    public override void Write(

            Utf8JsonWriter writer,

            Guid value,

            JsonSerializerOptions options) =>

                writer.WriteStringValue(value.ToString());

}

​

public class Post

{

    [JsonConverter(typeof(GuidJsonConverter))]

    public Guid AuthorId { get; set; }

​

    public string Title { get; set; }

}