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.Collections.Specialized;

using System.Web.Routing;

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;

​

    //http://stackoverflow.com/questions/43399303/turning-specific-object-fields-into-json

    public class CardListViewModel

    {

​

        public virtual Guid Id { get; set; }

​

​

        public virtual IEnumerable<Card> CardList { get; set; }

​

    }

​

    public class Card

    {

        public virtual Guid Id { get; set; }

​

        public virtual string IndexName { get; set; }

​

        public virtual Image CardImage { get; set; }

    }

​

    public class Image

    {

        public virtual string Src { get; set; }

    }

​

    public class CardListConverter : JsonConverter

    {

        public override bool CanConvert(Type objectType)

        {

            return typeof(IEnumerable<Card>).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 ICollection<Card> ?? new List<Card>();

            var obj = JObject.Load(reader);

            foreach (var property in obj.Properties())

            {

                list.Add(new Card { IndexName = property.Name, CardImage = new Image { Src = (string)property.Value } });

            }

            return list;

        }

​

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

        {

            var collection = (IEnumerable<Card>)value;

            writer.WriteStartObject();

            foreach (var item in collection)

            {

                writer.WritePropertyName(item.IndexName);

                writer.WriteValue(item.CardImage == null ? null : item.CardImage.Src);

            }

            writer.WriteEndObject();

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var CardListViewModel = new CardListViewModel

            {

                Id = new Guid("c2a7cc0f-0e6b-40a0-9020-aeba436265d4"),

                CardList = new List<Card>()

                {

                    new Card {Id = new Guid(5678, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), IndexName = "Visa", CardImage = new Image { Src = "Visa.png" }},

                    new Card {Id = new Guid(5555, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), IndexName = "MasterCard", CardImage = new Image { Src = "MasterCard.png" }}

                }

            };

​

            var settings = new JsonSerializerSettings

            {

                Converters = { new CardListConverter() },

            };

            var json = JsonConvert.SerializeObject(CardListViewModel, Formatting.Indented, settings);

​

            Console.WriteLine("Serialized {0}:", CardListViewModel);

            Console.WriteLine(json);

​

            var model2 = JsonConvert.DeserializeObject<CardListViewModel>(json, settings);

​

            var json2 = JsonConvert.SerializeObject(model2, Formatting.Indented, settings);

​

            Console.WriteLine("Deserialized and re-serialized {0}:", model2);

            Console.WriteLine(json2);

        }

    }

​

    public class Program

    {

        public static void Main()

        {

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

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

            Console.WriteLine("");

            TestClass.Test();

        }

    }