Create a middleware from an async function that transforms a request, with the given state.

See State for more details about accessing state.

Example

use axum::{
    Router,
    http::{Request, StatusCode},
    routing::get,
    response::IntoResponse,
    middleware::map_request_with_state,
    extract::State,
};

#[derive(Clone)]
struct AppState { /* ... */ }

async fn my_middleware<B>(
    State(state): State<AppState>,
    // you can add more extractors here but the last
    // extractor must implement `FromRequest` which
    // `Request` does
    request: Request<B>,
) -> Request<B> {
    // do something with `state` and `request`...
    request
}

let state = AppState { /* ... */ };

let app = Router::new()
    .route("/", get(|| async { /* ... */ }))
    .route_layer(map_request_with_state(state.clone(), my_middleware))
    .with_state(state);
# let _: axum::Router = app;