using System;

using System.IO;

using System.Text;

using System.Text.Json;

using System.Threading.Tasks;

using Microsoft.Extensions.Logging;

using Microsoft.Extensions.Options;

using Microsoft.Extensions.DependencyInjection;

using Microsoft.Extensions.Configuration;

using Microsoft.Extensions.Configuration.Json;

using System.Collections.Generic;

​

public class Program

{

    public static async Task Main()

    {

        var container = new ServiceCollection();

        container.AddLogging(b => b.AddConsole());

        container.AddOptions();

        var json = JsonSerializer.Serialize(new {

            Value2 = "value2",

            myOptions1 = new {

                Value = "value1"

            },

            myOptions2 = new {

                Value1 = "value2"

            },

            MyOptions = new {

                Value3 = "value3"

            },

            myOptions4 = new {

                MyOptions = new {

                    Value4 = "value4",

                    MyOptions = new {

                        Value4 = "level4"

                    }

                }

            }

        });

        await File.WriteAllTextAsync("appsettings.json", json);

        var config = new ConfigurationBuilder()

            .AddJsonFile("appsettings.json");

        var configuration = config.Build();

        container.AddSingleton<IConfiguration>(configuration);

        container.ConfigureMyOptions();

        container.Configure<MyOptions>(configuration);

        using(var scope = container.BuildServiceProvider().CreateScope())

        {

            var sp = scope.ServiceProvider;

            var logger = sp.GetRequiredService<ILogger<Program>>();

            var options = sp.GetRequiredService<IOptions<MyOptions>>().Value;

            logger.LogInformation(options.Value);

            logger.LogInformation(options.Value1);

            logger.LogInformation(options.Value2);

            logger.LogInformation(options.Value3);

            logger.LogInformation(options.Value4);

        }

        Console.WriteLine("Finished");

    }

}

​

public class MyOptions 

    {

        public string Value {get;set;} = "Default1";

        public string Value1 {get;set;} = "Default1";

        public string Value2 {get;set;} = "Default2";

        public string Value3 {get;set;} = "Default3";

        public string Value4 {get;set;} = "Default4";

    }

​

public static class OptionsExtensions 

{

    public static void ConfigureMyOptions(this IServiceCollection container, IConfiguration config = null)

    {       

        if(config == null)

        {

            var tmp = container.BuildServiceProvider();

            config = tmp.GetRequiredService<IConfiguration>();

            tmp.Dispose();

        }

        foreach(var section in config.GetChildren())

        {

            if(section.Key == nameof(MyOptions)) 

            {

                container.Configure<MyOptions>(section);

            }

            container.ConfigureMyOptions(section);

        }

    }

}