Path extractor documentation does not mention that multiple Path arguments should not be used

[uckelman]

• I have looked for existing issues (including closed) about this

Bug Report

Version

├── axum v0.6.20
│   ├── axum-core v0.3.4
│   ├── axum-macros v0.3.8 (proc-macro)

Platform

Linux scylla 6.5.10-200.fc38.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Nov  2 19:59:55 UTC 2023 x86_64 GNU/Linux

Description

A few days ago on Discord somebody posted code like the following, wondering why it doesn't work:

async fn handler(
    Path(package): Path<String>,
    Path(path): Path<String>,
) -> Result<(), AppError> {
    ....
}

 let app = axum::Router::new()
        .route("/:package/v1/*path", get(handler));

It's natural to see the Path extractor and think that you need one as an argument in your handler for each path component you want to capture. When I saw this, I knew exactly what the problem was, because I had exactly the same problem a few weeks ago.

While the documentation for Path does say that it extracts multiple components to tuples, it never says explicitly that you should not try to extract multiple components each with its own Path extractor like above. Saying this explicitly would head off a common confusion for new users.