using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var parent = new Parent(1);

        var child1 = new Child { Parent = parent };

        var child2 = new Child { Parent = parent };

        parent.Children.Add(child1);

        parent.Children.Add(child2);

​

        var data = new List<Child> { child1, child2 };

​

        var settings = new JsonSerializerSettings

        {

            PreserveReferencesHandling = PreserveReferencesHandling.Objects

        };

        var json = Newtonsoft.Json.JsonConvert.SerializeObject(data, Formatting.Indented, settings);

        Console.WriteLine(json);

​

        var data2 = Newtonsoft.Json.JsonConvert.DeserializeObject<IList<Child>>(json, settings);

        Console.WriteLine("\nFirst child's parent id is " + data2[0].Parent.Id);

        Console.WriteLine("Second child's parent id is " + data2[1].Parent.Id);

    }

}

​

public class Parent

{

    public Parent(int id)

    {

        Id = id;

    }

​

    [JsonConstructor]

    private Parent()

    { }

​

    [JsonProperty]

    public int Id { get; private set; }

    public IList<Child> Children { get; set; } = new List<Child>();

}

​

public class Child

{

    public Parent Parent { get; set; }

}

​