using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

    // https://stackoverflow.com/questions/56383331/how-to-iterate-through-a-nested-json-object-in-c#comment99367034_56383331

​

    // https://stackoverflow.com/questions/56383331/how-to-iterate-through-a-nested-json-object-in-c#comment99367034_56383331

​

    public partial class KeyIdObject

    {

        public string key { get; set; }

        public long T_id { get; set; }

        public List<KeyIdObject> Children { get; set; }

    }

​

    public partial class KeyIdObject

    {

        public static List<KeyIdObject> ToIdObjects(JToken root)

        {

            return root.TopDescendantsWhere<JObject>(o => o["T_id"] != null)

                .Select(o => new KeyIdObject { key = ((JProperty)o.Parent).Name, T_id = (long)o["T_id"], Children = ToIdObjects(o) })

                .ToList();

        }

    }

​

    public partial class KeyIdObject

    {

        // Generate clean JSON on re-serialization.

        public bool ShouldSerializeChildren() { return Children != null && Children.Count > 0; }

    }

​

    public static partial class JsonExtensions

    {

        /// <summary>

        /// Enumerates through all descendants of the given element, returning the topmost elements that match the given predicate

        /// </summary>

        /// <param name="root"></param>

        /// <param name="filter"></param>

        /// <returns></returns>

        public static IEnumerable<TJToken> TopDescendantsWhere<TJToken>(this JToken root, Func<TJToken, bool> predicate) where TJToken : JToken

        {

            if (predicate == null)

                throw new ArgumentNullException();

            return GetTopDescendantsWhere<TJToken>(root, predicate, false);

        }

​

        static IEnumerable<TJToken> GetTopDescendantsWhere<TJToken>(JToken root, Func<TJToken, bool> predicate, bool includeSelf) where TJToken : JToken

        {

            if (root == null)

                yield break;

            if (includeSelf)

            {

                var currentOfType = root as TJToken;

                if (currentOfType != null && predicate(currentOfType))

                {

                    yield return currentOfType;

                    yield break;

                }

            }

            var rootContainer = root as JContainer;

            if (rootContainer == null)

                yield break;

            var current = root.First;

            while (current != null)

            {

                var currentOfType = current as TJToken;

                var isMatch = currentOfType != null && predicate(currentOfType);

                if (isMatch)

                    yield return currentOfType;

​

                // If a match, skip children, but if not, advance to the first child of the current element.

                var next = (isMatch ? null : current.FirstChild());

​

                if (next == null)

                    // If no first child, get the next sibling of the current element.

                    next = current.Next;

​

                // If no more siblings, crawl up the list of parents until hitting the root, getting the next sibling of the lowest parent that has more siblings.

                if (next == null)

                {

                    for (var parent = current.Parent; parent != null && parent != root && next == null; parent = parent.Parent)

                    {

                        next = parent.Next;

                    }

                }

​

                current = next;

            }

        }

​

        static JToken FirstChild(this JToken token)

        {

            var container = token as JContainer;

            return container == null ? null : container.First;

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var json = GetJson();

​

            // Strip comments

            var root = JToken.Parse(json);

​

            var items = KeyIdObject.ToIdObjects(root);

​

            var newJson = JsonConvert.SerializeObject(items, Formatting.Indented);

​

            Console.WriteLine("Output List<KeyIdObject>: ");

            Console.WriteLine(newJson);

            Console.WriteLine("\nInput JSON: ");

            Console.WriteLine(json);

            // Assert we have exactly the same sequence of `T_id` integers in the mapped structure as in the original.

            Assert.IsTrue(JArray.Parse(newJson).SelectTokens("..T_id").Select(i => (long)i).SequenceEqual(root.SelectTokens("..T_id").Select(i => (long)i)));

        }

​

        static string GetJson()

        {

            var json = @"{

   ""Soccer"":{

      ""T_id"":0,

      ""T_state"":""valid"",

      ""Clubs"":{

         ""ClubA"":{

            ""T_id"":""1"",

            ""T_state"":""Champs""

         },

         ""ClubB"":{

            ""T_id"":""2"",

            ""T_state"":""Runnerups""

         }

      },

      ""Subs"":{

         ""SubA"":{

            ""T_id"":""3"",

            ""T_state"":""Unfit"",

            //this is nested key

            ""SubE"":{

               ""T_id"":""3"",

               ""T_state"":""Unfit""

            }

         }

      },

      ""Subs_Used"":{

         ""SubK"":{

            ""T_id"":""3"",

            ""T_state"":""Unfit""

         }

      }

      //many more nested n-levels   

   }

}";

            return json;

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

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

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​