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

CSharp · Console

/Program.cs

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 "";
		}
	}