How do I access state in middleware without redefining state?

[thomasmost]

I need my database pool in most of my auth middleware, but I don't want to recreate my state for each from_fn_with_state call — that would seem to defeat the purpose of State?

My state.rs file

use axum::extract::FromRef;
use bdata::db::Pool;

#[derive(Clone)]
pub struct AppState {
  pub pool: Pool,
}

impl FromRef<AppState> for Pool {
  fn from_ref(app_state: &AppState) -> Pool {
    app_state.pool.clone()
  }
}

The end of my main.rs file

  ...

  let app = routes.with_state(app_state);

  axum::Server::bind(&"0.0.0.0:8000".parse().unwrap())
    .serve(app.into_make_service())
    .await
    .unwrap();

A router file

pub fn configure() -> Router<AppState> {
  Router::<_>::new()
    .route("/test", get(routes_v1::test))
    .route_layer(axum::middleware::from_fn(middleware::session_user::auth)) // This errors with:
}
    
    // `axum::middleware::FromFn<fn(axum::extract::State<Pool<ConnectionManager<diesel::MysqlConnection>>>, http::Request<_>, Next<_>) -> impl std::future::Future<Output = Result<http::Response<http_body::combinators::box_body::UnsyncBoxBody<axum::body::Bytes, axum::Error>>, http::StatusCode>> {session_user::auth::<_>}, (), Route, _>: Service<http::Request<hyper::Body>>` is not satisfied
    

The abbreviated session user middleware:

pub async fn auth<B>(State(pool): State<Pool>, mut req: Request<B>, next: Next<B>) -> Result<Response, StatusCode> {
  let session_dao = &mut SessionDao::new(&pool);
  let user_dao = &mut UserDao::new(&pool);
  ...
  req.extensions_mut().insert(SessionUser(user));

  Ok(next.run(req).await)

[thomasmost]

Do I need to pass a clone of the state through to each router configuration function?

Would you recommend using Arc instead of cloning the database ool?

[davidpdrsn]

We document the options here https://docs.rs/axum/latest/axum/middleware/index.html#accessing-state-in-middleware

[davidpdrsn]

An sqlx pool is a reference counted pointed so that cheap to clone. I suppose "bunch of configs values" aren't expensive to clone either.

[uwejan]

Thank you. I am also running websockets server. I noticed memory increase to 500mb on 10 clients only. Going to make a debugging profile and see where this mem is coming from. Is thre any side notes on websockets?

[davidpdrsn]

Is thre any side notes on websockets?

No. Its unlikely to be axum's fault.

[uwejan]

Hey @davidpdrsn , I am implementing similar to the OP question. While in a normal middleware fromfnwithstate am able to cookie_jar: CookieJar, How can i access it with https://docs.rs/axum/latest/axum/middleware/index.html#accessing-state-in-middleware ?

[davidpdrsn]

Just add as an argument like any other extractor.