using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Converters;

using System.Text.Json;

​

var myObj = new { DOB = DateTime.Now.AddYears(-20) };

​

​

Console.WriteLine("Newtonsoft ->\t\t" + JsonConvert.SerializeObject(myObj, new NewtonsoftDateTimeConverter()));

​

var options = new JsonSerializerOptions();

options.Converters.Add(new SystemTextJsonDateTimeConverter());

​

Console.WriteLine("System.Text.Json ->\t" + System.Text.Json.JsonSerializer.Serialize(myObj, options));

​

​

Console.ReadKey();

​

public class NewtonsoftDateTimeConverter : DateTimeConverterBase

{

    public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, Newtonsoft.Json.JsonSerializer serializer)

    {

        throw new NotImplementedException();

    }

​

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

    {

        DateTime val = (DateTime)value;

        writer.WriteStartConstructor("Date");

        writer.WriteValue(val.Year);

        writer.WriteValue(val.Month - 1);

        writer.WriteValue(val.Day);

        writer.WriteValue(val.Hour);

        writer.WriteValue(val.Minute);

        writer.WriteValue(val.Second);

        writer.WriteValue(0);

        writer.WriteEndConstructor();

    }

}

​

public class SystemTextJsonDateTimeConverter : System.Text.Json.Serialization.JsonConverter<DateTime>

{

    public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)

    {

        throw new NotImplementedException();

    }

​

    public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)

    {

        writer.WriteStartObject("Date");

        writer.WriteNumberValue(value.Year);

        writer.WriteNumberValue(value.Month - 1);

        writer.WriteNumberValue(value.Day);

        writer.WriteNumberValue(value.Hour);

        writer.WriteNumberValue(value.Minute);

        writer.WriteNumberValue(value.Second);

        writer.WriteNumberValue(0);

        writer.WriteEndObject();

    }

}