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/65044079/json-null-changing-to-0-for-nullable-int-types

​

    namespace Common

    {

        public class CustomerInformation

        {

            public int? YearsofPurchase { get; set; }

            public int? Age{ get; set; }

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var binder = new KnownTypesBinder(new Dictionary<string, Type>{ {"Customer.CustomerInformation", typeof(Common.CustomerInformation) }});

​

            Func<JsonSerializerSettings> custDefualtSettings = () => new JsonSerializerSettings

            {

                TypeNameHandling = TypeNameHandling.All,

                TypeNameAssemblyFormatHandling = TypeNameAssemblyFormatHandling.Full,

                MissingMemberHandling = MissingMemberHandling.Ignore,

                DefaultValueHandling = DefaultValueHandling.Include,                

                NullValueHandling = NullValueHandling.Include,          

                SerializationBinder = binder, // Hack to make namespaces in JSON work.

            };

            Console.WriteLine(JsonConvert.SerializeObject(new Common.CustomerInformation(), custDefualtSettings()));

            var response = GetJson();

            var result = JsonConvert.DeserializeObject<Common.CustomerInformation>(response, custDefualtSettings());            

            result.Dump();

            Assert.AreEqual(null, result.Age);

            Assert.AreEqual(null, result.YearsofPurchase);

        }   

        static string GetJson()

        {

            return @"                     {

                        ""$id"": ""1"",

                        ""$type"": ""Customer.CustomerInformation, Customer.Common"",

                        ""CustomerId"": 103606055,                                                   

                        ""YearsofPurchase "": null,

                        ""Age"": null,

                        ""PhoneNumber"": """",

                        }

";

        }

    }

​

    public class KnownTypesBinder : ISerializationBinder

    {

        readonly Dictionary<string, Type> nameToType;

        readonly Dictionary<Type, string> typeToName;

​

        public KnownTypesBinder(IEnumerable<KeyValuePair<string, Type>> nameToType)

        {

            this.nameToType = nameToType.ToDictionary(p => p.Key, p => p.Value);

            this.typeToName = nameToType.ToDictionary(p => p.Value, p => p.Key);

        }

​

        public Type BindToType(string assemblyName, string typeName)

        {

            if(nameToType.TryGetValue(typeName, out var type))

                return type;

            throw new JsonSerializationException(string.Format("Unknown type name {0} ({1})", typeName, assemblyName));

        }

​

        public void BindToName(Type serializedType, out string assemblyName, out string typeName)

        {

            if (!typeToName.TryGetValue(serializedType, out typeName))

                throw new JsonSerializationException(string.Format("Unknown type {0}", serializedType));

            assemblyName = null;

        }

    }

​

    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;

        }

    }

​