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 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/75081574/cosmos-db-save-documents-with-interface-properties-net-sdk-v3-how-do-i-save-a

​

    public interface IMyCommand

    {

    }

​

    public class MyCommand1 : IMyCommand

    {

    }

​

    public class MyCommand2 : IMyCommand

    {

    }

​

    //partition key is CompanyId

    public class MyClass

    {

        [JsonProperty("id")]

        public Guid Id { get; set; }

​

        public string CompanyId { get; set; }

​

        [JsonProperty(ItemTypeNameHandling = TypeNameHandling.Auto)] // Add this

        public List<IMyCommand> Commands { get; set; }

​

        public MyClass(string partitionKey)

        {

            CompanyId = partitionKey;

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            string partitionKey = "Test";           

            var myclass = new MyClass(partitionKey)

            {

                Id = Guid.NewGuid(),

                Commands = new List<IMyCommand>

                {

                    new MyCommand1(),

                    new MyCommand2()

                }

            };

            var settings = new JsonSerializerSettings

            {

            };

​

            var json = JsonConvert.SerializeObject(myclass, settings);

            Console.WriteLine(json);

            var myclass2 = JsonConvert.DeserializeObject<MyClass>(json, settings);

            var json2 = JsonConvert.SerializeObject(myclass2, settings);

            Console.WriteLine(json2);

​

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

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

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

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​