using System;

using System.Text.Json;

using System.Text.Json.Serialization;

​

public class Program

{

    public static void Main()

    {

        var options = new JsonSerializerOptions

        {

            DefaultIgnoreCondition = JsonIgnoreCondition.Always, // this does not work 

        };

        var p = new Poco

        {

            Text = "hello",

            Value = 123

        };

        var s = JsonSerializer.Serialize(p, options);

            Console.WriteLine(s);

    }

    public class Poco

    {

        public string Text

            {

                get;

                set;

            }

​

            public long Value

            {

                get;

                set;

            }

    }

}