How do I return a service wrapped into MapRequest?

[ckruse]

Summary

I want to wrap my app creation into a function. The app wraps the router into a layer to enable URI rewriting:

    let middleware = axum::middleware::map_request_with_state(state.clone(), middlewares::current_forum::current_forum);

    let mut app: AppRouter = Router::new();
    app = controllers::configure(app);

    let app: Router = app
        .route_service("/favicon.ico", ServeFile::new(format!("{}/favicon.ico", static_path)))
        .route_service(
            "/humans.txt",
            ServeFile::new_with_mime(format!("{}/humans.txt", static_path), &mime::TEXT_PLAIN_UTF_8),
        )
        .route_service(
            "/robots.txt",
            ServeFile::new_with_mime(format!("{}/robots.txt", static_path), &mime::TEXT_PLAIN_UTF_8),
        )
        .nest_service("/static", ServeDir::new(static_path))
        .with_state(state);

    let app = middleware.layer(app);

But I can't return the created app, not with this layer neither as a service with middleware.layer(app).into_make_service() because the compiler constructs this type:

IntoMakeService<axum::middleware::MapRequest<fn(axum::extract::State<AppState>, http::Request<axum::body::Body>) -> impl std::future::Future<Output = http::Request<axum::body::Body>>, AppState, Router, (axum::extract::State<AppState>, http::Request<axum::body::Body>)>>

When trying to use this as a return type, the compiler says this:

error[E0562]: `impl Trait` only allowed in function and inherent method argument and return types, not in `fn` pointer return types
   --> src/lib.rs:157:14
    |
157 |         ) -> impl std::future::Future<Output = http::Request<axum::body::Body>>,
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Am I doing something wrong?

Best regards,
CK

axum version

0.7.4

[davidpdrsn]

I don't recommend attempting to do that. The generics make it very hard (as you've discovered). I recommend organizing your code such that you avoid having to name the type.

[ckruse]

Hm, in https://github.com/tokio-rs/axum/blob/main/examples/testing/src/main.rs#L34-L35 you do, don't you?

Ok, I will try to implement it in a different way, thank you for your recommendation. :-)

[davidpdrsn]

No, that returns a Router where the middleware type is erased.