What is Dependency Injection in ASP.NET Core?

Dependency Injection (DI) in ASP.NET Core is a technique to achieve Inversion of Control by providing dependencies to classes instead of creating them directly. DI enhances modularity, testability, and maintainability of applications.

Key Features:

• Supports built-in DI container
• Manages service lifetimes: Singleton, Scoped, Transient
• Integrates with controllers, Razor Pages, and middleware
• Reduces tight coupling between classes
• Makes unit testing easier

Example:
Registering services in Program.cs:

builder.Services.AddTransient<IEmailService, EmailService>();
var app = builder.Build();

Injecting a service into a controller:

public class HomeController : Controller
{
    private readonly IEmailService _emailService;

    public HomeController(IEmailService emailService)
    {
        _emailService = emailService;
    }

    public IActionResult Index()
    {
        _emailService.SendEmail("hello@example.com", "Test");
        return View();
    }
}

Dependency Injection in ASP.NET Core promotes loose coupling and improves application design, making apps easier to maintain and test.

Citations:

• Learn more on Savanka
• Official ASP.NET Core Documentation