Dependency injection in ASP.NET Core

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Dependency Injection (DI) is a design pattern that helps in creating loosely coupled applications. It allows developers to write clean, maintainable, and testable code.

Here is a step-by-step tutorial on how to implement Dependency Injection in ASP.NET Core.

  1. Create an ASP.NET Core web application:
dotnet new webapp -n MyWebApp
  1. Install the Microsoft.Extensions.DependencyInjection NuGet package:
dotnet add package Microsoft.Extensions.DependencyInjection
  1. Create an interface and a class that implements the interface. This is the class that we want to inject as a dependency. For example:
public interface IService
    string GetMessage();

public class Service : IService
    public string GetMessage()
        return "Hello from Service";
  1. In the Startup.cs file, add the following code in the ConfigureServices method to configure the dependency injection container:
public void ConfigureServices(IServiceCollection services)
    services.AddTransient<IService, Service>();
  1. Inject the dependency in a controller or any other class that needs it. For example, in the HomeController.cs file, add the following code:
public class HomeController : Controller
    private readonly IService _service;

    public HomeController(IService service)
        _service = service;

    public IActionResult Index()
        ViewData["Message"] = _service.GetMessage();
        return View();
  1. Finally, run the application and access the home page to see the message from the Service class.

That’s it! This is a basic example of Dependency Injection in ASP.NET Core. In a real-world scenario, you may have multiple dependencies, and you can add them to the dependency injection container in the same way.

Note: The AddTransient method creates a new instance of the Service class each time it is requested. There are also other methods available like AddSingleton and AddScoped to control the lifetime of the dependencies.

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