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 System.Text.Json;

using System.Text.Json.Serialization;

using System.Text.Json.Serialization.Metadata;

using System.Text.Json.Nodes;

using System.Threading.Tasks;

​

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

​

//https://stackoverflow.com/questions/77500839/deserialize-wrapper-of-generic-dtos

​

#nullable enable

​

public interface Dto<T> : Dto where T : Entity;

​

[JsonDerivedType(derivedType: typeof(CourseDto))]

[JsonDerivedType(derivedType: typeof(DeletedDto))]

[JsonPolymorphic(UnknownDerivedTypeHandling = JsonUnknownDerivedTypeHandling.FallBackToNearestAncestor)]

public interface Dto

{

    string Id { get; init; }

};

​

public interface Entity

{

}

​

public sealed record CourseEntity(Guid id, string Name) : Entity;

​

public sealed record DeletedDto(string Id) : Dto;

​

public sealed record CourseDto(

    string Id,

    string Name

) : Dto<CourseEntity>;

​

public sealed record SynchronizableWrapper<T>(T[]? Added, T[]? Updated, DeletedDto[]? Deleted)

    : SynchronizableWrapper(Added, Updated, Deleted) where T : class, Dto

{

    public new T[]? Added => (T[]?) base.Added;

    public new T[]? Updated => (T[]?) base.Updated;

    public new DeletedDto[]? Deleted => base.Deleted;

}

​

public record SynchronizableWrapper(Dto[]? Added, Dto[]? Updated, DeletedDto[]? Deleted)

{

    public Dto[]? Added { get; set; } = Added;

    public Dto[]? Updated { get; set; } = Updated;

    public DeletedDto[]? Deleted { get; set; } = Deleted;

}

​

    class TestClass

    {

        public static async Task Test()

        {

            var wrapper = await AsyncGetChangedEntities<CourseDto, CourseEntity>();

            var json2 = JsonSerializer.Serialize(wrapper, new JsonSerializerOptions { WriteIndented = true });

            Console.WriteLine("Re-serialized {0}:", wrapper);

            Console.WriteLine(json2);

        }   

        public static async Task<SynchronizableWrapper?> AsyncGetChangedEntities<T, T2>() where T : class, Dto<T2> where T2 : class, Entity

        {

            var stream = new MemoryStream(

                Encoding.UTF8.GetBytes(

                    """

                    {

                      "added": [

                        {

                          "id": "6a38a67c-46e3-497e-ab5f-3fa6b8d15cc4",

                          "name": "SomeCourse's name"

                        }

                      ],

                      "updated": [],

                      "deleted": [

                        {

                          "id": "6a38a67c-46e3-497e-ab5f-3fa6b8d15cc4"

                        }

                      ]

                    }

                    """));

​

            var _serializerOptions = new JsonSerializerOptions

            {

                PropertyNamingPolicy = JsonNamingPolicy.CamelCase,

            };

            return await JsonSerializer.DeserializeAsync<SynchronizableWrapper<T>>(stream, _serializerOptions);

        }

    }

​

    public class Program

    {

        public static async Task Main(string[] args)

        {

            Console.WriteLine("Environment version: {0} ({1}), {2}", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion);

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

            Console.WriteLine();

​

            try

            {

                await TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​