using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

​

public class Program

{

    public static void Main()

    {

        string json = @"

            {

                ""ID"": {

                    ""type"": ""integer"",

                    ""title"": ""ID Display Name""

                },

                ""TITLE"": {

                    ""type"": ""string"",

                    ""title"": ""Title Display name""

                },

                ""NAME"": {

                    ""type"": ""string"",

                    ""title"": ""Name""

                },

                ""CUSTOM_123"": {

                    ""type"": ""string"",

                    ""title"": ""CUSTOM_123"",

                    ""formLabel"": ""CUSTOM_123 Display Name""

                }

            }";

        IList<Field> fields = JsonConvert.DeserializeObject<IList<Field>>(json, new CustomJsonConverter());

        Console.WriteLine(fields.ElementAt(0).Title);

        Console.WriteLine(fields.ElementAt(1).Title);

        Console.WriteLine(fields.ElementAt(2).Title);

        Console.WriteLine(fields.ElementAt(3).Title);

    }

}

​

public class CustomJsonConverter : JsonConverter

{

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

    {

        throw new NotImplementedException();

    }

​

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

    {

        IList<Field> fields = new List<Field>();

        JObject obj = JObject.Load(reader);

        foreach (JToken child in obj.Children())

        {

            Field field = new Field();

            JProperty fieldProp = (JProperty)child;

            JObject fieldValue = (JObject)fieldProp.Value;

            string fieldName = fieldProp.Name;

            if (fieldName.StartsWith("CUSTOM_"))

            {

                field.Title = (string)fieldValue["formLabel"];

                field.Type = (string)fieldValue["type"];

            }

            else

            {

                field.Title = (string)fieldValue["title"];

                field.Type = (string)fieldValue["type"];

            }

​

            fields.Add(field);

        }

​

        return fields;

    }

​

    public override bool CanConvert(Type objectType)

    {

        return true;

    }

}

​

public class FieldWrapper

{

    public IList<Field> Fields

    {

        get;

    }

​

    = new List<Field>();

}

​

public class Field

{

    public string Title

    {

        get;

        set;

    }

​

    public string Type

    {

        get;

        set;

    }

}