using System;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

                ""MinValueAsString"" : 1.2,

            }";

        Foo foo = JsonConvert.DeserializeObject<Foo>(json);

        Console.WriteLine("MinValueAsString: " + foo.MinValueAsString);

​

        Console.WriteLine();

        json = JsonConvert.SerializeObject(foo);

        Console.WriteLine(json);

    }

}

​

class Foo

{

    public int MinValueAsString { get; set; }

}

​

public class DecimalJsonConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return (objectType == typeof(decimal));

    }

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

    {

        if (reader.TokenType == JsonToken.String)

        {

            string value = (string)reader.Value;

            if (value == string.Empty)

            {

                return decimal.MinValue;

            }

        }

        else if (reader.TokenType == JsonToken.Float || 

                 reader.TokenType == JsonToken.Integer)

        {

            return Convert.ToDecimal(reader.Value);

        }

        throw new JsonSerializationException("Unexpected token type: " + reader.TokenType.ToString());

    }

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

    {

        decimal dec = (decimal)value;

        if (dec == decimal.MinValue)

        {

            writer.WriteValue(string.Empty);

        }

        else

        {

            writer.WriteValue(dec);

        }

    }

}

​