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 System.Reflection;

using System.Collections.ObjectModel;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/66475252/c-sharp-webapi-json-overriding-for-custome-property

​

    public abstract class AbstractBase

    {

        [Key]

#if false

        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]

#endif

        public virtual int Id { get; set; }

​

        public virtual DateTime CreatedTimestamp { get; set; }

​

        public virtual DateTime UpdatedTimestamp { get; set; }

​

        [Required]

        public virtual int CreatedBy { get; set; }

​

        [Required]

        public virtual int LastModifiedBy { get; set; }

​

        public virtual bool ActiveFlag { get; set; }

​

        [JsonConverter(typeof(UserConverter))]

        public virtual User CreatedByUser { get; set; }

​

        [JsonConverter(typeof(UserConverter))]

        public virtual User LastModifiedByUser { get; set; }

​

#if false

        public MyAwaiter GetAwaiter()

        {

            return new MyAwaiter();

        }

#endif

        public string ToActiveInactive()

        {

            return this.ActiveFlag ? "Active" : "Inactive";

        }

    }

​

    public class Instance : AbstractBase

    {

    }

​

    public class User

    {

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public string GetFullName() => FirstName + " " + LastName;

    }

​

    public class UserConverter : JsonConverter<User>

    {

        public override void WriteJson(JsonWriter writer, User value, JsonSerializer serializer)

        {

            writer.WriteValue(value.GetFullName());

        }

​

        public override User ReadJson(JsonReader reader, Type objectType, User existingValue, bool hasExistingValue, JsonSerializer serializer)

        {

            var fullName = serializer.Deserialize<string>(reader);

            // Or construct a User and return it, if you can do so from the fullName.

            throw new NotImplementedException();

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var instance = new Instance

            {

                Id = 101, 

                CreatedTimestamp = new DateTime(2021, 1, 1),

                UpdatedTimestamp = new DateTime(2021, 3, 4),

                CreatedBy = 202, 

                CreatedByUser = new User { FirstName = "foo", LastName = "bar" },

                LastModifiedByUser = new User { FirstName = "Alice", LastName = "Bob" },

            };

            var json = JsonConvert.SerializeObject(instance, Formatting.Indented);

            Console.WriteLine(json);

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.Location.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​