使用命名注册解析实例不会引发异常

Question

I thought I know a lot about Unity, but the following scenario I did not except. I´m using Unity Container to register my views for Prism as objects with a named registration like so:

_unityContainer.RegisterType<object, MyDummyView>("MyDummyViewName");

and I request instance of the view by calling

object view = _unityContainer.Resolve<object>("MyDummyViewName");

So far so good. Now I found a bug in my system, cause I used the wrong name to resolve an instance of a view and I expected an exception to be thrown by Unity.

object view = _unityContainer.Resolve<object>("MyWrongDummyViewName");

But Unity does not throw any exception (like ResolutionFailedException or ActivationException ). It returns a new object , when I do the call above, without registering any view with the given (wrong) name.

Is this a correct behavior by Unity? I really expected to get an exception here. In the scope of Prism this is a problem, cause I won´t get any exceptions during navigation to a wrong target (view).

Answer 1

I'm with you that this is unexpected behavior. I think the problem origins from the fact that you are trying to resolve an instance of a concrete class (in your case object ). Looks like Unity will always try to resolve that instance. As long as it can do that it will ignore named mappings.

I experimented with a base class ( ViewBase ) which the container will also resolve unless you declare it abstract . Doing that raises the expected exception.

If you introduce an interface or abstract base class that should solve your problem.

You should open a bug ticket for Unity .