Unity InjectionFactory Doesn't Run

Question

Summary: It seems like the InjectionFactory is not being run for a type mapping. I'd like to know why and how to solve the problem.

At first, I tried to register the interface

Container.RegisterType<ILogger>(new InjectionFactory((c, t, n) => {
                return LogManager.GetLogger(n);
            }));

And resolve using the service locator

ServiceLocator.GetInstance<ILogger>("Operation Manager");

This resulted in

The current type, NLog.ILogger, is an interface and cannot be constructed. Are you missing a type mapping?

After some tinkering, I decided to try a different approach and registered the service using the concrete type instead

Container.RegisterType<Logger>(new InjectionFactory((c, t, n) => {
                    return LogManager.GetLogger(n);
                }));

And changed the resolution method to

public OperationService([Dependency("Operation Service")]Logger logger)

This results in the following error:

 The type Logger does not have an accessible constructor.

The only reason I can think of for this behavior is if the function I've passed via the InjectionFactory isn't actually being called to resolve the object.

Answer 1

This is because you registered the type without a name, and you're trying to resolve it by name. Unity looks for a registration for (ILogger, "Operation Manager") , but it can't find any. Your registration with no name is never considered an eligible candidate, so the InjectionFactory is not called.

As far as I know, there's no built-in way to achieve what you're trying to do. It might be possible with a custom extension, but my attempts so far have been unsuccessful.