using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

using System.Threading;

using System.Collections.ObjectModel;

using System.Reflection;

using System.Text.RegularExpressions;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;            

    // https://stackoverflow.com/questions/41553379/display-json-object-array-in-datagridview

​

    public class Items

    {

        public int num { get; set; }

        public int average { get; set; }

        public bool state { get; set; }

        public int id { get; set; }

        public int buy { get; set; }

        public string name { get; set; }

    }

​

    class TestClass

    {

        static string GetJson()

        {

            var json = @"{

""2"": {

  ""num"": 5,

  ""average"": 10,

  ""state"": true,

  ""id"": 2,

  ""buy"": 10,

  ""name"": ""name""

 },

""6"": {

  ""num"": 5,

  ""average"": 10,

  ""state"": true,

  ""id"": 6,

  ""buy"": 20,

  ""name"": ""name""

 }

}";

            return json;

        }

​

        static string GetJson2()

        {

            var json = @"{

""9"": {

  ""num"": 5,

  ""average"": 10,

  ""state"": true,

  ""id"": 9,

  ""buy"": 20,

  ""name"": ""name""

 },

""2"": {

  ""num"": 5,

  ""average"": 10,

  ""state"": true,

  ""id"": 2,

  ""buy"": 10,

  ""name"": ""name""

 },

""6"": {

  ""num"": 5,

  ""average"": 10,

  ""state"": true,

  ""id"": 6,

  ""buy"": 20,

  ""name"": ""name""

 }

}";

            return json;

        }

​

        internal static void Test()

        {

            Test(GetJson());

            Test(GetJson2());

        }

​

        private static List<Items> Test(string json)

        {

            Console.WriteLine("Initial JSON: ");

            Console.WriteLine(json);

​

            var dict = JsonConvert.DeserializeObject<SortedDictionary<int, Items>>(json);

​

            var objlis = JsonConvert.DeserializeObject<List<Items>>(json, new ListToDictionaryConverter<Items>());

​

            var json21 = JsonConvert.SerializeObject(objlis, Formatting.Indented);

            Console.WriteLine("Deserialized and reserialized as an ARRAY: ");

            Console.WriteLine(json21);

​

            var json22 = JsonConvert.SerializeObject(objlis, Formatting.Indented, new ListToDictionaryConverter<Items>());

            Console.WriteLine("Deserialized and reserialized as an OBJECT: ");

            Console.WriteLine(json22);

​

            if (!JToken.DeepEquals(JToken.Parse(json), JToken.Parse(json22)))

            {

                Console.WriteLine("Initial and re-serialized JSON are NOT equivalent.");

                throw new InvalidOperationException("(!JToken.DeepEquals(JToken.Parse(json), JToken.Parse(json22)))");

            }

            else

            {

                Console.WriteLine("Initial and re-serialized JSON are equivalent.");

            }

​

            return objlis;

        }

    }

​

    public class ListToDictionaryConverter<T> : JsonConverter where T : class

    {

        public override bool CanConvert(Type objectType)

        {

            return typeof(List<T>).IsAssignableFrom(objectType);

        }

​

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

        {

            if (reader.TokenType == JsonToken.Null)

                return null;

            var list = existingValue as List<T> ?? (List<T>)serializer.ContractResolver.ResolveContract(objectType).DefaultCreator();

            if (reader.TokenType == JsonToken.StartArray)

                serializer.Populate(reader, list);

            else if (reader.TokenType == JsonToken.StartObject)

            {

                var dict = serializer.Deserialize<Dictionary<int, T>>(reader);

                foreach (var pair in dict)

                    list.SetOrAddAt(pair.Key, pair.Value, default(T));

            }

            else

            {

                throw new JsonSerializationException(string.Format("Invalid token {0}", reader.TokenType));

            }

            return list;

        }

​

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

        {

            var list = (IList<T>)value;

            writer.WriteStartObject();

            for (int i = 0; i < list.Count; i++)

            {

                // Omit null values.

                if (list[i] == default(T))

                    continue;

                writer.WritePropertyName(((JValue)i).ToString());

                serializer.Serialize(writer, list[i]);

            }

            writer.WriteEndObject();

        }

    }

​

    public static class ListExtensions

    {

        public static void SetOrAddAt<T>(this IList<T> list, int index, T value, T defaultValue = default(T))

        {

            if (list == null)

                throw new ArgumentNullException("list");

            list.EnsureCount(index + 1, defaultValue);

            list[index] = value;

        }

​

        public static void EnsureCount<T>(this IList<T> list, int count, T defaultValue = default(T))

        {

            if (list == null)

                throw new ArgumentNullException("list");

            int oldCount = list.Count;

            if (count > oldCount)

            {

                for (int i = oldCount; i < count; i++)

                    list.Add(defaultValue);

            }

        }

    }

​

    public class Program

    {

        public static void Main()

        {

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

​

            TestClass.Test();

        }

    }

​