using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Serialization;

using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

      var inputJson = @"{

    ""full_name"": ""John Smith"",

    ""total_price"": 20

}";

      var inputDto = JsonConvert.DeserializeObject<InputObjectDTO>(

        inputJson, 

        new JsonSerializerSettings { ContractResolver = new SnakeCaseContractResolver() }

      );

      Console.WriteLine( "{0}: {1}", inputDto.FullName, inputDto.TotalPrice );

    }

    [SnakeCased]

    public class InputObjectDTO {

      public string FullName { get; set; }

      public int TotalPrice { get; set; }

    }

​

    [AttributeUsage(AttributeTargets.Class)]

    public class SnakeCasedAttribute : Attribute {

      public SnakeCasedAttribute() {

        // intended blank

      }

    }

​

    public class SnakeCaseConverter : JsonConverter {

      public override bool CanConvert(Type objectType) {

          return objectType.GetCustomAttributes(true).OfType<SnakeCasedAttribute>().Any() == true;

      }

      private static string ConvertFromSnakeCase(string snakeCased) {

        return string.Join("", snakeCased.Split('_').Select(part => part.Substring(0, 1).ToUpper() + part.Substring(1)));

      }

​

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

        var target = Activator.CreateInstance( objectType );

        var jobject = JObject.Load(reader);

​

        foreach (var property in jobject.Properties()) {

          var propName = ConvertFromSnakeCase(property.Name);

          var prop = objectType.GetProperty(propName);

          if (prop == null || !prop.CanWrite) {

            continue;

          }

          prop.SetValue(target, property.Value.ToObject(prop.PropertyType, serializer));

        }

        return target;

      }

​

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

        throw new NotImplementedException();

      }

    }

​

    public class SnakeCaseContractResolver : DefaultContractResolver {

      public static readonly SnakeCaseContractResolver Instance = new SnakeCaseContractResolver();

      protected override JsonContract CreateContract(Type objectType) {

        JsonContract contract = base.CreateContract(objectType);

​

        if ( objectType.GetCustomAttributes(true).OfType<SnakeCasedAttribute>().Any() ) {

          contract.Converter = new SnakeCaseConverter();

        }

​

        return contract;

      }

    }

}