c# Json.NET ToJson() FromJson()

Question

I understand the value of creating an external JsonConverter classes however in many cases I find it unnecessarily cumbersome.

Is there a general way to tell JSon.NET that if a class has a string ToJson() method use that for serialization and if the class has a void FromJson(string json) method use that for deserialization ?

Or/And also for immutable types if a class has a static T FromJson(string json) use that ?

Answer 1

We need a special conveter:

namespace Newtonsoft.Json {
  class JsonManualConverter : JsonConverter {
    public override bool CanConvert(Type t) => t.GetMethod("ToJson") != null && t.GetMethod("FromJson") != null;

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) =>
      objectType.GetMethod("FromJson").Invoke(new object(), new object[] { JRaw.Create(reader).ToString() });

    public override void WriteJson(JsonWriter writer, object o, JsonSerializer serializer) =>
      writer.WriteRawValue(o.GetType().GetMethod("ToJson").Invoke(o, new object[] { }) as string);
  }
}

Then we can simply do:

  [JsonConverter(typeof(JsonManualConverter))]
  class MyClass {
    public string ToJson() => // serialize and return json string
    static public MyClass FromJson(string json) => // deserialize and return a MyClass instance
    ...
  }

and Json.Net will use these methods