How to access the request in fallback and error handlers?

[FelixZY]

Summary

I would like to be able to access the incoming request in fallback and error handlers. For example,

Router::new()
    .method_not_allowed_fallback(|| async { todo!("I want to get the request method in here!") })
    .layer(CatchPanicLayer::custom(|error| -> Response<i64> {
        todo!("I want to access the x-request-id header here!")
    }))

How can I do this?

axum version

0.7.9

[mladedav]

You should be able to use all extractors (including Request) in the same way as in any other handler.

[jplatte]

Well, not for the CatchPanic middleware. It's probably easiest for this sort of use case to replace it with a from_fn middleware. I might post an example later.

[FelixZY]

Examples would be most appreciated 🙂

[jplatte]

Something like this should work:

use axum::{
    extract::Request,
    middleware::{self, Next},
};
use futures_util::FutureExt as _;

Router::new()
    .method_not_allowed_fallback(|method: http::Method| async move {
        dbg!(method);
        http::StatusCode::METHOD_NOT_ALLOWED.into_response()
    })
    .layer(middleware::from_fn(|request: Request, next: Next| async move {
        let req_id = request.headers().get("x-request-id").cloned();
        match next.run(request).catch_unwind().await {
            Ok(response) => response,
            Err(panic_payload) => {
                dbg!(panic_payload);
                http::StatusCode::INTERNAL_SERVER_ERROR.into_response()
            }
        }
    }))

[FelixZY]

Thank you!