using System;

using System.Collections.Generic;

using System.Text.Json.Serialization;

using System.Text.Json;

public class Program

{

    public static void Main()

    {

        {

            var initial = new Ownership()

            {

                OwnershipId = "ID001",

                TextOutput = new List<string> { "hello", "goodbye" },

                DateTime = DateTime.UtcNow,

                MeanInterval = TimeSpan.FromHours(32)

            };

            Console.WriteLine("Initial: Total Days is {0}", initial.MeanInterval.TotalDays);

            string json = JsonSerializer.Serialize(initial, new JsonSerializerOptions() { WriteIndented = false });

            Console.WriteLine(json);

            var deserialized = JsonSerializer.Deserialize<Ownership>(json);

            Console.WriteLine("Deserialized: Total Days is {0}", deserialized.MeanInterval.TotalDays);

        }

        Console.WriteLine();

        Console.WriteLine();

        {

            TestObject to = new TestObject()

            {

                WithAttribute = TimeSpan.FromSeconds(30),

                WithoutAttribute = TimeSpan.FromSeconds(30)

            };

            string json = JsonSerializer.Serialize(to, new JsonSerializerOptions() { WriteIndented = true });

            Console.WriteLine(json);

        }       

    }

    public class TestObject

    {

        [JsonConverter(typeof(TimeSpanConverter))]

        public TimeSpan WithAttribute {get;set;}

        public TimeSpan WithoutAttribute {get;set;}

    }

    public class Ownership

    {

        public string OwnershipId { get; set; }

        public List<string> TextOutput { get; set; }

        public DateTime DateTime { get; set; }

        [JsonConverter(typeof(TimeSpanConverter))]

        public TimeSpan MeanInterval { get; set; }// Like long ticks, TimeSpan.FromTicks(Int64), TimeSpan.Ticks

    }

​

    public class TimeSpanConverter : JsonConverter<TimeSpan>

    {

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

        {

            return TimeSpan.FromTicks(reader.GetInt64());

        }

​

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

        {

            writer.WriteNumberValue(value.Ticks);

        }

    }

}