using System;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace JsonSerialization
{
	public static class Program
	{
		public static void Main()
		{
			const string json = @"{ ""InitOnly"": "".NET"", ""Settable"": ""Rocks"" }";

			var tagLine1 = JsonSerializer.Deserialize<TagLine>(json);
			Console.WriteLine(tagLine1.InitOnly ?? "tagLine1.InitOnly is null");
			Console.WriteLine(tagLine1.Settable ?? "tagLine1.Settable is null");

			Console.WriteLine();

			var tagLine2 = JsonSerializer.Deserialize<TagLine>(json, TagLineJsonContext.Default.TagLine);
			Console.WriteLine(tagLine2.InitOnly ?? "tagLine2.InitOnly is null");
			Console.WriteLine(tagLine2.Settable ?? "tagLine2.Settable is null");
		}
	}

	public sealed class TagLine
	{
		public string InitOnly { get; init; }   // This is always null when deserialized with TagLineJsonContext
		public string Settable { get; set; }
	}

	[JsonSerializable(typeof(TagLine), GenerationMode = JsonSourceGenerationMode.Metadata)]
	public partial class TagLineJsonContext : JsonSerializerContext
	{
	}
}