using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

​

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

// https://stackoverflow.com/questions/49659528/specyfing-default-value-for-a-property-in-relation-to-other-property-in-json-net

​

    public partial class JsonsoftExample

    {

        public JsonsoftExample() { }

​

        [JsonConstructor]       

        JsonsoftExample(DateTime start, DateTime? end)

        {

            this.Start = start;

            this.End = end ?? Start.AddHours(1);            

        }

        [JsonProperty(Required = Required.Always)]

        public DateTime Start { get; set; }

        public DateTime End { get; set; }

    }

​

    public partial class JsonsoftExample

    {       

        public string SomeOtherUnrelatedProperty { get; set; }

​

        public bool ShouldSerializeEnd()

        {

            return End != Start.AddHours(1);

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var start = DateTime.Parse("2017-10-11T12:34:34Z", CultureInfo.InvariantCulture);

            Test(start, start);

            Test(start, start.AddHours(2));

            Test(start, start.AddHours(1));

            try

            {

                var badJson = @"{""End"":""2017-10-11T14:34:34+00:00""}";

                Console.WriteLine("\nTesting JSON: ");

                Console.WriteLine(badJson);

                var example3 = JsonConvert.DeserializeObject<JsonsoftExample>(badJson);

                Assert.IsTrue(false, "Exception should have been thrown.");

            }

            catch (JsonException ex)

            {

                Console.WriteLine("Caught expected exception: " + ex.Message);

            }

        }

        public static void Test(DateTime start, DateTime end)

        {

            var example = new JsonsoftExample

            {

                Start = start,

                End = end,

                SomeOtherUnrelatedProperty = "some other unrelated property",

            };

            var json = JsonConvert.SerializeObject(example);

            Console.WriteLine("\nTesting JSON: ");

            Console.WriteLine(json);

            var example2 = JsonConvert.DeserializeObject<JsonsoftExample>(json);

            Assert.IsTrue(example.Start == example2.Start, "start");

            Assert.IsTrue(example.End == example2.End, "end");

            Assert.IsTrue(example.SomeOtherUnrelatedProperty == example2.SomeOtherUnrelatedProperty, "SomeOtherUnrelatedProperty");

            Console.WriteLine("{0} deserialized successfully.", example2);

        }

    }

​

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

        public AssertionFailedException(string s) : base(s) { }

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            IsTrue(value, "failed");

        }

​

        public static void IsTrue(bool value, string message)

        {

            if (value == false)

                throw new AssertionFailedException(message ?? "failed");

        }

    }

​