Running a middleware before the router?

[TimNN]

Hi, I've recently started experimenting with Gotham and so far have to say Thank You, for an awesome library! Now to my issue:

If I understand my debug logs correctly, any middleware I add to a Router will only run if the Router successfully matches a route. I have a middleware¹ I want to run irrespective of whether the Router has any matching routes (or rather, I want the middleware to run before the Router).

Is there a standard way of doing this?

I haven't had the time yet to experiment, but I've thought of the following approaches:

• "Manually" wrap the middleware around the Router by implementing (New)Handler.
• Use PipelineHandleChain to do the same.
• Use two nested Routers: The outer one has the middleware I want to run and a * delegation to the inner router (not sure if that would work).

¹: The actual use case is that I want to reject all unauthenticated requests with a 403. If the request is authenticated, I want the normal 404 handling of the router to take place. If Gotham has other ways to deal with this, I'd be happy to hear about them.

[TimNN]

So, I went with approach (2) by defining two types

struct PreMiddlewareWrapper<C, P, NH> {
    pipeline_chain: C,
    pipelines: PipelineSet<P>,
    new_handler: NH,
}

struct PreMiddlewareHandler<C, P, H> {
    pipeline_chain: C,
    pipelines: PipelineSet<P>,
    handler: H,
}

and associated NewHandler / Handler implementations (which was pretty straightforward, except for figuring out the correct bounds on everything).

Would there be interest in having something like this in Gotham? If so I can send a pull request with the implementation. (Which module would be most appropriate for this code?)

[whitfin]

Hey @TimNN! This has actually come up a couple of times I think; I've never been sure on whether middleware fires on 404s or not. If it's indeed true that they don't, it seems like this should be something we support officially somehow - so it might be worth PR'ing what you wrote up for discussion.

Curious what @colinbankier and @nyarly think!

[colinbankier]

Thanks @TimNN. Yep - I think this is certainly an interesting case that we don't have a good answer for yet. I'm wondering if this also gives us an avenue to handle CORS/OPTIONS gracefully, i.e. #119.
Your idea sounds great. Yep, I think you're right that your 3rd option, using nested routers, probably wouldn't work off the top of my head, so option 2 sounds most promising.
We'd love a PR with what you have so far :)
Would be interesting to see how we can incorporate this idea in way that is intuitive and consistent with the middleware / pipeline apis.