using System;

using Newtonsoft.Json;

​

public class Program

{

    public class FlagConverter : JsonConverter

    {

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

        {

            writer.WriteValue(value.ToString());

        }

​

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

        {

            if (reader.Value is string)

            {

                return (string)reader.Value != "F";

            }

            else if (reader.Value is bool)

            {

                return (bool)reader.Value;

            }

            else

                throw new Exception("Bad");

        }

​

        public override bool CanConvert(Type objectType)

        {

            return objectType == typeof(bool);

        }

    }

    public class Order

    {

        [JsonConverter(typeof(FlagConverter))]

        [JsonProperty("flag_value")]

        public bool FlagValue {get;set;}

    }

    public static void Main()

    {

        var order = JsonConvert.DeserializeObject<Order>("{ \"flag_value\": 'T' }");

        Console.WriteLine(order.FlagValue);

        order = JsonConvert.DeserializeObject<Order>("{ \"flag_value\": 'F' }");

        Console.WriteLine(order.FlagValue);

        order = JsonConvert.DeserializeObject<Order>("{ \"flag_value\": true }");

        Console.WriteLine(order.FlagValue);

        order = JsonConvert.DeserializeObject<Order>("{ \"flag_value\": false }");

        Console.WriteLine(order.FlagValue);

    }

}