using System;

using System.Linq;

using System.Collections.Generic;

using System.ComponentModel;

using Newtonsoft.Json;

​

public class Program

{

    public static void Main()

    {

        var inputs = new List<object>()

        {new Foo{Prop2 = "" , Bar = new Bar()}};

        foreach (object input in inputs)

        {

            string NormalSerialisation = JsonConvert.SerializeObject(input, Formatting.Indented, new JsonSerializerSettings{});

            string CustomSerialisation = JsonConvert.SerializeObject(input, Formatting.Indented, new JsonSerializerSettings{NullValueHandling = NullValueHandling.Ignore, DefaultValueHandling = DefaultValueHandling.Ignore});

            Console.WriteLine("normal:");

            Console.WriteLine(NormalSerialisation);

            Console.WriteLine("custom:");

            Console.WriteLine(CustomSerialisation);

        }

    }

​

    public class Foo

    {

        public string Prop2

        {

            get;

            set;

        }

​

        public Bar Bar

        {

            get;

            set;

        }

    }

​

    public class Bar

    {

        [DefaultValue("")]

        public string Prop2;

    }

}