using System;

using Newtonsoft.Json;

​

public class Program

{

    public static void Main()

    {

        var obj = new Person

        {

            FirstName = "John", 

            LastName = "Smith", 

            Json = "{ \"Age\": 30 }"

        };

        var s = JsonConvert.SerializeObject(obj);

        s.Dump();

        var obj2 = JsonConvert.DeserializeObject(s, typeof(Person)) as Person;

        obj2.Dump();

        Console.WriteLine(obj.Json);

        Console.WriteLine(obj2.Json);

    }

}

​

public class Person

{

    public string FirstName

    {

        get;

        set;

    }

​

    public string LastName

    {

        get;

        set;

    }

​

    [JsonConverter(typeof(StringToJsonConverter))]

    public string Json

    {

        get;

        set;

    }

}

​

public class StringToJsonConverter : JsonConverter

{

    public override bool CanConvert(Type t)

    {

        throw new NotImplementedException();

    }

​

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

        var o = JsonConvert.DeserializeObject(value.ToString());

        serializer.Serialize(writer,o);

    }

​

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

        var o = serializer.Deserialize(reader);

        return JsonConvert.SerializeObject(o);

    }

}