Using property injection instead of constructor injection

Question

Long story short, I'm trying to use ELMAH with MVC 2 and Ninject, and I need to use parameterless constructors. I created an initial post about it here: Using a parameterless controller constructor with Ninject?

I was advised to use property injection instead of constructor injection. So I moved from this:

public class DepartmentsController : Controller
{
    private IDepartmentsRepository departmentsRepository;

    public DepartmentsController(IDepartmentsRepository departmentsRepository)
    {
        this.departmentsRepository = departmentsRepository;
    }

    ...
}

to this:

public class DepartmentsController : Controller
{
    private IDepartmentsRepository _departmentsRepository;

    [Inject]
    public IDepartmentsRepository DepartmentsRepository
    {
        get { return _departmentsRepository; }
        set { _departmentsRepository = value; }
    }

    ...
}

But in my other controller functions, whether I try to access DepartmentsRepository or _departmentsRepository, I get an object reference not set to an instance of an object error when I try to access it.

Is there something else I need to do here?

Answer 1

I had a similar problem. Have a look at my questions: Using Ninject with Membership.Provider.

Basically when you initialise DepartmentsController you need to injectthis (i.e. your departments controller into your Ninject kernal. So its something like:

public class DepartmentsController : Controller
{
  private IDepartmentsRepository _departmentsRepository;

  [Inject]
  public IDepartmentsRepository DepartmentsRepository
  {
    get { return _departmentsRepository; }
    set { _departmentsRepository = value; }
  }

  public DepartmentsController()
  {
    NinjectHelper.Kernel.Inject(this);
  }
}

Where NinjectHelper in this case gets the current Ninject Kernel.