ASP.NET MVC proper layering of application and dependency injection

Question

I have a project that has three layer.

1st is the DAL

2nd is the Domain

3rd is the Presentation

I created an interface in my Domain Layer (ICategoryRepository) here is the Code

public interface ICategoryRepository
{
    List<CategoryDTO> GetCategory();
}

and I created a class in my DAL to implement the ICategoryRepository in my Domain.

public class CategoryRepository : ICategoryRepository
{                     
    BookInfoContext _context;

    public List<CategoryDTO> GetCategory()
    {
        _context = new BookInfoContext();

        var categoryDto = _context.Categories
                            .Select(c => new CategoryDTO
                            {
                                CategoryId = c.CategroyId,
                                CategoryName = c.CategoryName
                            }).ToList();
        return categoryDto;
    }
}

Then I create a class in my Domain and pass the ICategoryRepository as parameter in my constructor.

public class CategoryService
{

    ICategoryRepository _categoryService;

    public CategoryService(ICategoryRepository categoryService)
    {
        this._categoryService = categoryService;
    }

    public List<CategoryDTO> GetCategory()
    {
        return _categoryService.GetCategory();
    }
}

I do this to invert the control. Instead of my domain will depend on DAL I invert the control so that myDAL will depend on my DOMAIN.

My Problem is, everytime I call the CategoryService in the Presentation Layer I need to pass ICategoryRepository as parameter of constructor which is in the DAL. I don't want my Presentation Layer to be dependent in my DAL.

Any suggestion?

Thanks,

Felipe Oriani · Accepted Answer · 2013-07-19 11:29:25Z

1

You could use a dependency injection. In asp.net mvc we have a IDepencyResolver interface that inject dependencies on controllers dependencies and its dependencies. To do this, you will need a container to be easy to inject your dpendencies, for sample, MS Unity, Ninject, etc.. and register all types on your container to it knows how to resolve your dependencies.

With a Container and DependencyResolver setted, you can have a dependency of your service on your controller, for sample:

public class CategoryController
{
   private readonly ICategoryService _categoryService;

   // inject by constructor..
   public CategoryController(ICategoryService categoryService)
   {
       _categoryService = categoryService;
   }


   public ActionResult Index()
   {
      var categories = _categoryService.GetCategory();

      return View(categories);
   }

}

In this case, the Container will see the controller need the service and this service need a repository. It will resolve everything for your, since your have registred these types.

Take a look at this article: http://xhalent.wordpress.com/2011/01/17/using-unity-as-a-dependency-resolver-asp-net-mvc-3/

answered Jul 19, 2013 at 11:29

Felipe Oriani

38.7k20 gold badges141 silver badges203 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

RAM Over a year ago

Do I need to change anything in my categoryService..? I try that code and it will return null value. I use ninject to resolve the dependencies but when I try to bind I get errors.. I am binding using this code kernel.Bind<ICategoryService>().To<CategoryService>();

Felipe Oriani Over a year ago

I do not know about ninject, but as any container, you have to register all dependencies: Repositories and Services, to Container know how to resolve all dependencies on the tree: controller -> service -> repository. Did you register your repository?

RAM Over a year ago

You're right I just need to register my repository.. kernel.Bind<ICategoryRepository>().To<CategoryRepository>(); <br/>. My problem now is my Presentation Layer has a dependency to my DAL.. Thanks bro for the help

Felipe Oriani Over a year ago

Nice, but just a tip, does not create any dependency on your View, just ViewModels geekswithblogs.net/michelotti/archive/2009/10/25/…

Collectives™ on Stack Overflow

ASP.NET MVC proper layering of application and dependency injection

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related