Middleware process_resource isn't called for sinks

[mcm]

This may be intentional, but I couldn't find anything in docs to confirm that other than some discussion on #691... even there, though, it wasn't necessarily clear that this behavior's intentional.

If we have a process_resource method on middleware, it's not called when a sink is matched, since resource is None inside of api.__call__. Personally I would consider a sink to be a resource, but really I'm just looking for clarification about whether they should be (and in that case, is this behavior a bug) or should not be (and then maybe just a note added to the docs).

[kgriffs]

Hi @mcm, I can see how a sink might be considered a resource in the abstract, but in terms of implementation, the former is universal responder method, while the latter is a collection of responders wrapped in a class. Therefore, a given process_resource() method would have to distinguish between the two.

I can think of a couple of ways we might handle this, but before we get into that, could you elaborate on your particular use case? Do you need a reference to the sink callable, or do you have some logic that you only want to run when a resource or a sink matches the requested URL path?

[kgriffs]

We now have three types of routes supported by the framework:

• Resources
• Sinks
• Static files

It may make sense after all to provide a way for middleware components to hook requests that end up matching any of the above, rather than only providing a way to intercept requests to resources.

[Sylphe88]

I was a bit suprised to see that process_resource is not called for sinks!
My use case: serving files behind a prefixed route: GET /api/v1/images/.*
Because the files may be stored in a file tree (say, foo/bar/dog.png), I though a sink would be good, but then it broke my auth middleware.

[vytas7]

Hi @Sylphe88!
Yeah, that's the way it currently works...

As a workaround for authentication middleware you might be able to leverage process_request() instead, that is called for all incoming requests.

[Sylphe88]

I changed how the route URI is formed so I can use resources instead of sinks, the result is cleaner. process_request() would have been the other way to go but then again existing middlewares (e.g. falcon-auth) mostly rely on process_resource() for better performance, so they won't be called for sinks