Dependency Injection in .NET with examples?

Question

Can someone explain dependency injection with a basic .NET example and provide a few links to .NET resources to extend on

Answer 1

Create DB layer project(class library) and add below code in it.

public class UserData : IUserData
{
    public string getUserDetails()
    {
        return "Asif";
    }
}

public interface IUserData
{
    string getUserDetails();
}

Answer 2

Add bussiness logic project of type class library and add below code in it. public class UserDetailLogic : IUserDetailLogic { private IUserData _userData = null;

    public UserDetailLogic(IUserData userData)
    {
        _userData = userData;
    }
    public string getUserDetails()
    {
        return _userData.getUserDetails();
    }
}

public interface IUserDetailLogic
{
    string getUserDetails();
}

In you main project add below code in home controller.

public class HomeController : Controller { private readonly IUserDetailLogic _userDetailLogic;

    public HomeController(IUserDetailLogic userDetailLogic)
    {
        _userDetailLogic = userDetailLogic;
    }

    public ActionResult Index()
    {
        ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application.";
        string str = _userDetailLogic.getUserDetails();
        return View();
    }

    public ActionResult About()
    {
        ViewBag.Message = "Your app description page.";

        return View();
    }

    public ActionResult Contact()
    {
        ViewBag.Message = "Your contact page.";

        return View();
    }
}