Fix UsersResponderV1 to return None and not an exception when user not found

[subotic]

When a user is not found, then the UsersResponderV1 should return None and not a NotFoundException which is translated to into a 404 status code .

[benjamingeer]

I thought we decided that NotFoundException and the 404 are correct?

[benjamingeer]

In #315 I've changed UsersResponderV1 so it doesn't use Option anymore, and just throws an exception if a requested user is not found. I also changed Authenticator to handle this change. Please let me know if this looks OK to you.

[subotic]

Yes, this is fine for now. I opened this issue before and completely forgot about it.

I say for now, because I thing that the responder should return an option, and the route should then throw an exception, if it want's. This way, we decouple the routes behaviour from the responder.

Generally speaking, I see two different use cases for a responder:

(1) Requesting something through the route, which should return Not Found when the IRI is not correct,

(2) Internal use, by asking one responder from another for something. The response in this case should be preferably None.

But to support both cases in this manner, we would need to refactor RouteUtil a bit, so that the result from the responder is returned to the calling route, and then the route needs to throw the exception or create a HttpResponse in a separate step.

[benjamingeer]

Thanks for looking at this. Currently when responders talk to each other, they can get NotFoundException if they ask for something (a resource, a value) that doesn't exist. This simplifies things for them, because if a responder gets a NotFoundException from another responder, the normal case is that the exception is just returned to the client. Since that's done automatically, there's no need for the (receiving) responder or the route to do anything about it. Currently I don't think we have any cases where a responder asks for something from another responder and it's OK if it doesn't exist.

[subotic]

Currently I don't think we have any cases where a responder asks for something from another responder and it's OK if it doesn't exist.

Up until now ;-) But since the user-management2 branch is in constant flux, this can change. I will keep you posted.

[benjamingeer]

OK :) It's not hard to change this if we need to.

[subotic]

I thought about this a bit more. If this is needed only in rare cases, then we could probably write a method that turns the result/exception into an Option. This way, we don't need to refactor the responders themselves.

Also, I had already made these changes in the user-management2 branch, but your refactoring of the Authenticator is much nicer and better :-)