Per-route middleware

[tirr-c]

This PR adds per-route middleware support. Current design is as follows:

• Route::middleware applies given middleware to the route.
• Following Route::method (and Route::all) will apply middleware given before.
• Middleware list for the route can be reset using Route::reset_middleware.
• When Route::at is called, per-route middleware applied to the parent will be applied to the child route by default. This can be reset using .reset_middleware().

Feel free to comment if there is better design!

---

Closes #320.

[yoshuawuyts]

Subroutes returned by Route::at won't have any middleware applied.

I would expect the following to work:

let mut app = tide::new();
app.middleware(middleware_a());

app.at("/").get(|req| "hi"); // middleware "a" applies here

app.at("/foo")
    .middleware(middleware_b())
    .get(|req| "hello");  // middleware "a" + b" apply here

app.listen("localhost:8080").await?;

This is also so that top-level middleware such as logging, cookie handling and others will always be able to run. Being able to define per-route, and per-app middleware is generally desirable. Does it work like this?

[yoshuawuyts]

Also the following:

let mut outer = tide::new();
outer.middleware(middleware_a());
outer.at("/foo").get(|req| "hello");  // middleware "a" applies here

let mut inner = tide::new();
inner.middleware(middleware_b());
inner.at("/").get(|req| "hi"); // middleware "a" + "b" apply here

outer.nest(inner);
outer.listen("localhost:8080").await?;

[tirr-c]

@yoshuawuyts Ah, I meant per-route middleware is reset -- yeah, per-app middleware will remain applied. I'll add some tests to cover those!

[yoshuawuyts]

@tirr-c Can you share an example of what you mean? I don't have a clear understanding of the rules quite yet.

[tirr-c]

@yoshuawuyts I meant like this:

let mut app = tide::new();
app.middleware(MiddlewareGlobal); // This is app-global and won't be reset
app.at("/a")
    .middleware(MiddlewareA) // This is per-route and subject to be reset
    .get(echo_path) // Global + A
    .at("/b") // /a/b, A is removed here
    .middleware(MiddlewareB)
    .get(echo_path); // Global + B

(and you mentioned the wrong person 😅)

[yoshuawuyts]

Lol oops, yeah typing from the mobile app.

Hmm, yeah I think I would expect that to work still, even if I probably wouldn't write it like that myself. Route "b" is nested under "a", so hierarchically I'd expect all of the middleware from "a" to apply to "b".

[tirr-c]

@yoshuawuyts That's the alternative approach I wrote. If you feel it's better, I'll change the behavior!

[yoshuawuyts]

Yess, thank you — that'd be great!

[tirr-c]

@yoshuawuyts Ooh I misunderstood your first code! It's quite tough to apply middleware of the parent if the subroute is created without using Route::at, e.g. calling app.at("/parent") and app.at("/parent/child") separately. I'm going to make subroutes middleware work only when it's called like app.at("/parent").at("/child"). Is it okay to do so?

[yoshuawuyts]

I think that's ok! As long as the global middleware still works. I think using at as a means of nesting works well!

[tirr-c]

@yoshuawuyts Done! Tests are added to ensure what works and what doesn't.

[yoshuawuyts]

This is 💯

Thanks so much!!