Resolving dependency injected service as part of builder when specifying options-CodePudding

I'm using Microsoft.Extensions.DependencyInjection in my ASP.NET Core project (targeting .NET 7.0).

I have a service that, provided a sizable number of injected other services, yields a string value that I need in order to populate an options method during my DI registrations. Typically, I'd simply have DI inject the service into any of the controllers in which I'd pull the various values needed, but here the situation is a bit different.

Here, I am using one of those many helpful extension methods of IServiceCollection that themselves register their own various types, but it also exposes an action that allows me to specify some settings. I need to resolve a string value from my aforementioned service that I can use in the option specification method later on.

This extension method isn't something I have written, but part of a third-party library and it itself is quite extensive (e.g. not something I want to write/maintain my own version of). The extension itself looks like the following:

builder.Services.AddMySpecialService().SpecifyOptions(opt => {
  opt.Id = "<Insert DI string value here>";
});

Ideally, I need to inject the service in such a way so as to pass that string value into my settings, but short of creating a local instance (not really feasible given all its own dependencies), I'm at a loss of how I'd go about this, if it's even possible at all.

Has anyone successfully done this and if so, how? Thanks!

CodePudding user response：

Without knowing what that third-party library is, you can use dependencies when configuring your options in a standard way.

using System;

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder
    .Services
    .AddSingleton<IStringProviderService, StringProviderService>()
    .AddOptions<MyOptions>()
    // For .Configure() method you can specify up to 5 dependencies.
    .Configure<IStringProviderService>(
        (myOptions, stringProviderService) =>
        {
            myOptions.Id = stringProviderService.GetString();
        }
    );

public class MyOptions
{
    public required string Id { get; set; }
}

public interface IStringProviderService
{
    string GetString();
}

public class StringProviderService : IStringProviderService
{
    string IStringProviderService.GetString()
    {
        return Guid.NewGuid().ToString("N");
    }
}