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.Threading.Tasks;

using System.Threading;

​

using System.Text.Json;

using System.Text.Json.Serialization;

​

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

​

//https://stackoverflow.com/questions/67318988/how-can-i-deserialize-some-subtree-only

​

    public class MyType

    {

        public string Foo { get; set; }

    }

​

    public static partial class JsonSerializerExtensions

    {

        public static T DeserializeAnonymousType<T>(string json, T anonymousTypeObject, JsonSerializerOptions options = default)

            => JsonSerializer.Deserialize<T>(json, options);

​

        public static ValueTask<TValue> DeserializeAnonymousTypeAsync<TValue>(Stream stream, TValue anonymousTypeObject, JsonSerializerOptions options = default, CancellationToken cancellationToken = default)

            => JsonSerializer.DeserializeAsync<TValue>(stream, options, cancellationToken); // Method to deserialize from a stream added for completeness

    }

​

    class TestClass

    {

        public static void Test()

        {

            var jsonString = GetJson();

            var myType = JsonSerializerExtensions.DeserializeAnonymousType(jsonString, 

                                                                           new { outer = new { inner = default(MyType) } })

                ?.outer?.inner;

            var newJson = JsonSerializer.Serialize(myType);

            Console.WriteLine(newJson);

            Assert.AreEqual("Value Of Foo", myType?.Foo);

        }

        static string GetJson() => @"{

   ""outer"":{

      ""inner"":{ ""Foo"" : ""Value Of Foo"" }

   }

}";

    }

​

    public class Program

    {

        public static void Main()

        {

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

            Console.WriteLine("System.Text.Json version: " + 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 "";

        }

    }

​