using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    private static JsonSerializerSettings JsonSettings = new JsonSerializerSettings() 

        { 

            TypeNameHandling = TypeNameHandling.All,

            TypeNameAssemblyFormat = System.Runtime.Serialization.Formatters.FormatterAssemblyStyle.Full // I think this is just needed because of dotnetfiddle oddness

        };

    public static void Main()

    {

        var item = new Child("hello", "world", new List<string>() { "some", "stuff" });

        var checkMe = GetItem<Parent>(GetSerialized(item));

        Console.WriteLine("{0} - {1}", DateTime.UtcNow, IsOfType(checkMe));

    }

    public static string GetSerialized(Child item)

    {

        return JsonConvert.SerializeObject(item, JsonSettings);

    }

    public static T GetItem<T>(string json)

    {

        return (T) GetItemFromJson(json, typeof(T));

    }

    public static object GetItemFromJson(string json, Type t)

    {

        return JsonConvert.DeserializeObject(json, t, JsonSettings);

    }

    public static bool IsOfType(Parent item)

    {

        return DoCheck(item);

    }

    private static bool DoCheck(Parent item)

    {

        return item is Child;

    }

}

​

​

public class Parent

{

    public string A { get; set; }

    public Parent(string a)

    {

        this.A = a;

    }

}

​

​

public class Child : Parent

{

    public string B { get; set; }

    public ICollection<string> Stuff { get; set; }

    public Child(string a, string b, ICollection<string> items)

        : base(a)

    {

        this.B = b;

        this.Stuff = items;

    }

}