using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        A a = new A();

        a.Str1 = "foo";

        a.Bs = new List<B>();

        a.Bs.Add(new B(a));

        a.Bs.Add(new B(a));

        a.Bs.Add(new B(a));

        JsonSerializerSettings settings = new JsonSerializerSettings

        {

            PreserveReferencesHandling = PreserveReferencesHandling.Objects,

            Formatting = Formatting.Indented

        };

        Console.WriteLine("---- serialize ----");

        var json = JsonConvert.SerializeObject(a, settings);

        Console.WriteLine(json);

        Console.WriteLine("---- deserialize ----");

        var newA = JsonConvert.DeserializeObject<A>(json, settings);

    }

}

​

public class A

{

    public string Str1 { get; set; }

    public IList<B> Bs { get; set; }

}

​

public class B

{

    [JsonProperty]

    private A a;

    public B(A a)

    {

        this.a = a;

        Console.WriteLine(a != null ? a.Str1 : "a is null");

    }

}

​