JSON.Net Struct Serialization Discrepancy

Question

When using JSON.Net to serialize/deserialize structs, a build-in struct type (like System.Drawing.Size) serializes to a string, whereas a custom struct type serializes to a JSON object.

For example:

using System;
using System.Drawing;
using Newtonsoft.Json;

namespace TestJsonNet
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(JsonConvert.SerializeObject(new Size(50, 50)));
            Console.WriteLine(JsonConvert.SerializeObject(new Size2(50, 50)));
        }
    }

    struct Size2
    {
        public int Width { get; set; }
        public int Height { get; set; }
        public Size2(int w, int h) : this()
        {
            Width = w; Height = h;
        }
    }
}

Outputs the following:

"50, 50"
{"Width":50,"Height":50}

I can understand the thinking behind serializing a struct to a string, since the memory layout is always the same; however, why the discrepancy when serializing a custom struct?

Also, I would (for internal legacy reasons), like to have JSON.Net serialize structs like the latter case (i.e. as JSON, not string). If it's possible, how can that be achieved?

Answer 1

Using reflection you could solve this problem. I took part of the solution you suggested yourself and used reflection to get the property names and values.

class StructConverter : JsonConverter
{
    public override void WriteJson(
        JsonWriter writer, object value, JsonSerializer serializer)
    {
        var myObject = (object)value;
        var jObject = new JObject();

        Type myType = myObject.GetType();
        IList<PropertyInfo> props = new List<PropertyInfo>(myType.GetProperties());

        foreach (PropertyInfo prop in props)
        {

            jObject.Add(prop.Name, prop.GetValue(myObject, null).ToString());
        }
        serializer.Serialize(
            writer,  jObject);
    }

....

    public override bool CanConvert(Type objectType)
    {
        return objectType.IsValueType;
    }
}