What methods and approaches do you know for implementing dependency injection in application controllers?

Dependency Injection (DI) in application controllers in C# can be implemented in several ways:

1. Through the constructor — the most common and recommended method. Dependencies are passed via the controller's constructor parameters.

public class MyController : Controller
{
    private readonly IService _service;

    public MyController(IService service)
    {
        _service = service;
    }

    public IActionResult Index()
    {
        // Using _service
        return View();
    }
}

2. Through properties (Property Injection) — dependencies are set via the controller's properties. Less preferred, as dependencies may not be initialized in time.

public class MyController : Controller
{
    [Inject]
    public IService Service { get; set; }
}

3. Through methods (Method Injection) — dependencies are passed as method parameters.

public IActionResult Index([FromServices] IService service)
{
    // Using service
    return View();
}

In ASP.NET Core, the built-in DI container supports all these methods, but constructor injection is the cleanest and most convenient for testing.