using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Diagnostics;

using System.IO;

using System.Threading;

using System.Collections.ObjectModel;

using System.Reflection;

using System.Runtime.Serialization;

using System.Data;

using System.ComponentModel;

using System.Globalization;

using System.Runtime.Serialization.Formatters.Binary;

using System.Collections.Specialized;

using System.Web.Routing;

using System.Net.Mail;

using System.Runtime.InteropServices;

using System.Text.RegularExpressions;

using System.Net;

using System.Runtime.Serialization.Formatters;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;

using System.Web.SessionState;

​

    // https://stackoverflow.com/questions/42723879/intercept-list-population-to-assign-values-in-deserialization

​

​

    public class CartItems : Collection<CartItem>

    {

        public CartItems() : base() { }

​

        public CartItems(CartItem parent) : this()

        {

            this.Parent = parent;

        }

​

        public CartItem Parent { get; private set; }

​

        protected override void RemoveItem(int index)

        {

            CartItem oldItem = null;

            if (index >= 0 && index < Count)

            {

                oldItem = this[index];

            }

​

            base.RemoveItem(index);

        }

​

        protected override void InsertItem(int index, CartItem item)

        {

            base.InsertItem(index, item);

            if (item != null)

                item.Parent = this;

        }

​

        protected override void SetItem(int index, CartItem item)

        {

            CartItem oldItem = null;

            if (index >= 0 && index < Count)

            {

                oldItem = this[index];

            }

​

            base.SetItem(index, item);

​

            if (oldItem != null)

                oldItem.Parent = null;

​

            if (item != null)

                item.Parent = this;

        }

​

        protected override void ClearItems()

        {

            foreach (var item in this)

                if (item != null)

                    item.Parent = null;

            base.ClearItems();

        }

​

    }

​

    public class CartItem

    {

        public CartItem()

        {

            this.Children = new CartItems(this);

        }

​

        public int t { get; set; }

        public int i { get; set; }

        public int n { get; set; }

        public bool r { get; set; }

        [JsonProperty("c")]

        public CartItems Children { get; private set; }

​

        [JsonIgnore]

        public CartItems Parent { get; set; }

    }

​

    public static class CartItemExtensions

    {

        public static IEnumerable<CartItem> DescendantsAndSelf(this CartItem item)

        {

            if (item == null)

                yield break;

            yield return item;

            foreach (var child in item.Children)

                yield return child;

        }

​

        public static IEnumerable<CartItem> DescendantsAndSelf(this IEnumerable<CartItem> items)

        {

            if (items == null)

                return Enumerable.Empty<CartItem>();

            return items.SelectMany(i => i.DescendantsAndSelf());

        }

    }

​

    class TestClass

    {

        static string GetJson()

        {

            var json = @"[{""t"":1,""i"":1,""n"":4,""r"":false,""c"":[{""t"":5,""i"":2,""n"":4,""r"":false,""c"":[]}]},{""t"":1,""i"":3,""n"":4,""r"":false,""c"":[{""t"":5,""i"":4,""n"":4,""r"":false,""c"":[{""t"":4,""i"":6,""n"":14,""r"":false,""c"":[]}]},{""t"":1,""i"":5,""n"":15,""r"":false,""c"":[]}]}]";

            return json;

        }

​

        internal static void Test()

        {

            var cookieContent = GetJson();

​

            var root = JsonConvert.DeserializeObject<CartItems>(cookieContent);

​

            Console.WriteLine("Re-serialized JSON: ");

            Console.WriteLine(JsonConvert.SerializeObject(root, Formatting.Indented));

​

            foreach (var parent in root.DescendantsAndSelf())

            {

                Assert.IsTrue(parent.Children.Parent == parent);

                foreach (var child in parent.Children)

                    Assert.IsTrue(child.Parent == parent.Children);

            }

​

            // Verify that Parent as set as items are removed and added

            var oldItem = root[0];

            var newItem = root[0] = new CartItem();

            Assert.IsTrue(oldItem.Parent == null);

            Assert.IsTrue(root[0].Parent == root);

​

            root.Clear();

​

            Assert.IsTrue(newItem.Parent == null);

            Console.WriteLine("All parent relationships are set correctly.");

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

        public AssertionFailedException(string s) : base(s) { }

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            if (value == false)

                throw new AssertionFailedException("failed");

        }

    }

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine("");

            TestClass.Test();

        }

    }

​