using Newtonsoft.Json;

using System;

public class Program

{

    private static JsonSerializerSettings jsonSerializerSettings = new JsonSerializerSettings

    {

        TypeNameHandling = TypeNameHandling.None

    };

​

    public static void Main()

    {

        var son = new Son();

        son.Age = "6";

        son.Gender ="m";

        var person = new Person

        {

            Name = "John Doe",

            child = son

        };

Console.WriteLine(person.child.GetType());

​

        var serialized = JsonConvert.SerializeObject(person, jsonSerializerSettings);

        Console.WriteLine(serialized);

        /* try

        {

            JsonConvert.DeserializeObject(

                @"{""$type"":""Person, abcdefgh.exe"",""Name"":""John Doe""}",

                jsonSerializerSettings);

        }

        catch (Exception ex)

        {

            Console.WriteLine($"{ex.GetType().Name}: {ex.Message}");

        } */    

    }

}

​

public class Child 

{

    public string Age {get; set;}

}

​

public class Son : Child 

{

    public string Gender {get; set;}

}

​

public class Person

{

    public string Name { get; set; }

    public Child child { get; set; }

}