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/68643556/json-net-custom-contractresolver-ignoring-custom-objects

​

​

​

    public class ParentClass

    {

        public string Item1 { get; set; }

        public CustomModel Item2 { get; set; }

    }

​

    public class CustomModel

    {

        public string CustomItem1 { get; set; }

        public string CustomItem2 { get; set; }

    }

​

    public class ChildClass : ParentClass

    {

        public string Item3 { get; set; }

        public string Item4 { get; set; }

    }

​

    public class CustomResolver : DefaultContractResolver

    {

        protected override List<MemberInfo> GetSerializableMembers(Type objectType)

        {

            return base.GetSerializableMembers(objectType).Where(member => member.DeclaringType == typeof(ParentClass) || typeof(ParentClass).IsSubclassOf(member.DeclaringType)).ToList();

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var instance = new ChildClass()

            {

                Item1 = "abc",

                Item2 = new CustomModel()

                {

                    CustomItem1 = "def",

                    CustomItem2 = "ghi"

                },

                Item3 = "jkl",

                Item4 = "mno",

            };

​

            var settings = new JsonSerializerSettings

            {

                ContractResolver = new CustomResolver(),

            };

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

            Console.WriteLine(json);        

        }   

        static string GetJson()

        {

            return @"

";

        }

    }

​

    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;

        }

    }

​