using System;

using System.Data;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var json = @"

{

  ""fechaGrabacionODH"": {

    ""$date"": 1634689986082

  }

}";

        Console.WriteLine(JsonConvert.DeserializeObject<DateObject>(json).fechaGrabacionODH);

    }

}

​

class DateObject{

    [JsonConverter(typeof(EpochConverter))]

    public DateTime fechaGrabacionODH;

}

​

public class EpochConverter : JsonConverter

{

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

    {

        var jObject = new JObject();

        jObject["$date"] = new DateTimeOffset((DateTime)value).ToUnixTimeMilliseconds();

        jObject.WriteTo(writer);

    }

​

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

    {

        var jObject = JObject.Load(reader);

        var epoch = jObject.GetValue("$date").Value<long>();

        return DateTimeOffset.FromUnixTimeMilliseconds(epoch).UtcDateTime;

    }

​

    public override bool CanRead

    {

        get { return true; }

    }

​

    public override bool CanConvert(Type objectType){ return objectType == typeof(DateTime); }

}