bgenc.net/content/posts/actix-web-import-issue.md

---
title: Solving `app_data` or `ReqData` missing in requests for actix-web
date: 2022-03-26
---

> This post is day 5 of me taking part in the
> [#100DaysToOffload](https://100daystooffload.com/) challenge.

I'm using `actix-web` to set up a web server, and I've been hitting a small
problem that I think other people may come across too.

To explain the problem, let me talk a bit about my setup. I have a custom
middleware that checks if a user is authorized to access a route. It looks like
this:

```rust
impl<S: 'static, B> Service<ServiceRequest> for CheckLoginMiddleware<S>
where
    S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error>,
    S::Future: 'static,
{
    type Response = ServiceResponse<EitherBody<B>>;
    type Error = Error;
    type Future = LocalBoxFuture<'static, Result<Self::Response, Self::Error>>;

    dev::forward_ready!(service);

    fn call(&self, req: ServiceRequest) -> Self::Future {
        let state = self.state.clone();
        let (request, payload) = req.into_parts();
        let service = self.service.clone();

        let user_token = get_token_from_header(&request);
        let path_token = if self.allow_path_tokens {
            get_token_from_query(&request)
        } else {
            None
        };

        Box::pin(async move {
            match verify_auth(state, user_token, path_token, request.path()).await {
                Ok(authorized) => {
                    tracing::debug!("Request authorized, inserting authorization token");
                    // This is the "important bit" where we insert the authorization token into the request data
                    request.extensions_mut().insert(authorized);
                    let service_request =
                        service.call(ServiceRequest::from_parts(request, payload));
                    service_request
                        .await
                        .map(ServiceResponse::map_into_left_body)
                }
                Err(err) => {
                    let response = HttpResponse::Unauthorized().json(err).map_into_right_body();

                    Ok(ServiceResponse::new(request, response))
                }
            }
        })
    }
}
```

The `verify_auth` function is omitted, but the gist of it is that it returns an `Result<Authorized, Error>`.
If the user is authorized, the authorization token `verify_auth` returned is then attached to the request.

Then here's how I use it in a path:

```rust
#[delete("/{store}/{path:.*}")]
async fn delete_storage(
    params: web::Path<(String, String)>,
    // This parameter is automatically filled with the token
    authorized: Option<ReqData<Authorized>>,
) -> Result<HttpResponse, StorageError> {
    let (store, path) = params.as_ref();

    let mut store_path = get_authorized_path(&authorized, store)?;
    store_path.push(path);
    if fs::metadata(&store_path).await?.is_file() {
        tracing::debug!("Deleting file {:?}", store_path);
        fs::remove_file(&store_path).await?;
    } else {
        tracing::debug!("Deleting folder {:?}", store_path);
        fs::remove_dir(&store_path).await?;
    }
    Ok(HttpResponse::Ok().finish())
}
```

This setup worked for this path, but would absolutely not work for another path.
I inserted logs to track everything, and just found that the middleware would
insert the token, but the path would just get `None`. How‽ I tried to slowly
strip everything away from the non-functional path until it was identical to
this one, but it still would not work.

Well it turns out the solution was very simple, see this:

```rust
use my_package::storage::put_storage;
use crate::storage::delete_storage;
```

Ah! They are imported differently. I had set up my program as both a library and
a program for various reasons. However, it turns out importing the same thing
from `crate` is different from importing it from the library. Because of the
difference in import, Actix doesn't recognize that the types match, so the route
can't access the attached token.

The solution is normalizing the imports. I went with going through the library
for everything, because that's what `rust-analyzer`s automatic import seems to
prefer.

```rust
use my_package::storage::{put_storage, delete_storage};
```

Solved!