Why is my Interface not being found?

Question

I'm getting, "The type or namespace name 'INRBQDeliveryRepository' could not be found (are you missing a using directive or an assembly reference?)" here:

public class DeliveryController : ApiController
{
    private readonly INRBQDeliveryRepository _deliveryRepository;

The interface type I'm trying to reference there is:

namespace SeaStore.Data.Legacy.Interfaces
{
    public interface INRBQDeliveryRepository
    . . .

These are different projects in a solution (NRBQ.Web is trying to access its sibling, SeaStore.Data.Legacy); adding "using SeaStore.Data.Legacy.Interfaces;" to the class that prevents compilation with the "not found" error doesn't help - in fact, I go from the error noted above to getting an addition error, specifically:

"The type or namespace name 'Data' does not exist in the namespace 'SeaStore' (are you missing an assembly reference?)" in the Controller class here:

using SeaStore.Data.Legacy.Interfaces;

Why is my other-project interface not visible?

Answer 1

The error message you received is kind of selfexplanatory: are you missing an assembly reference.

It indicates that you are actually missing a reference to an assembly.

Add --> Reference --> Locate the library where your interface is defined, and add the reference.

The using should resolve itself then, because it can now find the namespace. Which means you can use your interface!