using System.Text.Json;

​

namespace SerializeToFileAsync

{

    public class WeatherForecast

    {

        public DateTimeOffset Date { get; set; }

        public int TemperatureCelsius { get; set; }

        public string? Summary { get; set; }

    }

​

    public class Program

    {

        public static async Task Main()

        {

            var weatherForecast = new WeatherForecast

            {

                Date = DateTime.Parse("2019-08-01"),

                TemperatureCelsius = 25,

                Summary = "Hot"

            };

​

            string fileName = "WeatherForecast.json";

            using FileStream createStream = File.Create(fileName);

            await JsonSerializer.SerializeAsync(createStream, weatherForecast);

            await createStream.DisposeAsync();

​

            Console.WriteLine(File.ReadAllText(fileName));

        }

    }

}

// output:

//{"Date":"2019-08-01T00:00:00-07:00","TemperatureCelsius":25,"Summary":"Hot"}