using System;

using System.Collections.Generic;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string json = @"{

            ""PM00000001"": { ""description"": ""Manufacturing"",""cost"": -1,""group"":""Manufacturing"",""WeldAngleDegrees"": 60},

            ""PM00000010"": {""description"": ""Plate Roll"",""cost"": 90,""unit"": ""hr"",""group"": ""Roll"",""setup"": 0.5,""speed"": 0.4},

            ""PM00000011"": {""description"": ""Weld SAW"",""cost"": 90,""unit"": ""hr"",""group"": ""Weld"",""width"": 0.5,""thickness"": 50}

        }";

        var dict = JsonConvert.DeserializeObject<Dictionary<string, Item>>(json, new ItemConverter());

        foreach (var kvp in dict)

        {

            Console.WriteLine(kvp.Key);

            Console.WriteLine(kvp.Value + "\n");

        }

    }

}

​

public class Item

{

    public string description { get; set; }

    public double cost { get; set; }

    public string group { get; set; }

    public override string ToString()

    {

        return string.Format("description: {0}\ncost: {1}\ngroup: {2}", description, cost, group);

    }

}

​

public class ManufacturingItem : Item

{

    public string WeldAngleDegrees { get; set; }

    public override string ToString()

    {

        return string.Format("{0}\nweld angle: {1}", base.ToString(), WeldAngleDegrees);

    }

}

​

public class RollItem : Item

{

    public double setup { get; set; }

    public double speed { get; set; }

    public override string ToString()

    {

        return string.Format("{0}\nsetup: {1}\nspeed: {2}", base.ToString(), setup, speed);

    }

}

​

public class WeldItem : Item

{

    public double width { get; set; }

    public double thickness { get; set; }

    public override string ToString()

    {

        return string.Format("{0}\nwidth: {1}\nthickness: {2}", base.ToString(), width, thickness);

    }

}

​

public class ItemConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return objectType == typeof(Item);

    }

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

    {

        JObject jo = JObject.Load(reader);

        string group = (string)jo["group"];

        if (group == "Manufacturing")

        {

            return jo.ToObject<ManufacturingItem>();

        }

        else if (group == "Roll")

        {

            return jo.ToObject<RollItem>();

        }

        else if (group == "Weld")

        {

            return jo.ToObject<WeldItem>();

        }

        throw new JsonSerializationException("Unexpected item (group) type");

    }

    public override bool CanWrite

    {

        get { return false; }

    }

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

    {

        throw new NotImplementedException();

    }

}

​