Passing two parameters to a function, one of which is multipart: Multipart

[Lucky-49]

Hello everyone!
I have a problem: I need to convert the file sent by the client. I tried to write like this:

let route_convert = Router::new()
        .route("/upload", post(upload_file));

async fn upload_file(
      Path(output_format): Path<&str>,
      multipart: Multipart,
    ) -> impl IntoResponse {

but the compiler throws an error. How do I correctly accept a file from the client and an additional parameter that will indicate which format to convert to?

[mladedav]

You might want to post the error you're getting.

[jplatte]

Extractors can't borrow anything. Use Path<String>, not Path<&str>.

[Lucky-49]

How easily the problem was solved!!!! Thank you very much!!

[Lucky-49]

It wasn't that simple. ((
Now I get an error and don't understand what I'm doing wrong.

error[E0277]: the trait bound `fn(axum::extract::Path<std::string::String>, Multipart) -> impl Future<Output = std::result::Result<DownloadFile, error::Error>> {handler_convert_file}: Handler<_, _>` is not satisfied
   --> src\main.rs:22:47
    |
22  |         .route("/upload/:output_format", post(handler_convert_file));
    |                                          ---- ^^^^^^^^^^^^^^^^^^^^ the trait `Handler<_, _>` is not implemented for fn item `fn(Path<String>, Multipart) -> impl Future<Output = ...> {handler_convert_file}`

Please help me figure it out.
The code is here https://github.com/Lucky-49/untitled123

[mladedav]

Try adding #[debug_handler] to the handler function. It should provide a better error message than rustc.

Also, your link is broken, it points somewhere else but even if I copy it it returns 404.

[Lucky-49]

https://github.com/Lucky-49/untitled123

[mladedav]

Still 404. Is it possible the repository is private?

Did you try adding the debug_handler attribute to your function?

[Lucky-49]

Sorry, I didn't pay attention to the privacy of the repository.
Yes, I used #[debug_handler].

) -> Result<DownloadFile> { | ^^^^^^ the traitIntoResponseis not implemented forDownloadFile, which is required by std::result::Result<DownloadFile, error::Error>: IntoResponse`

) -> Result {
| ^^^^^^ required by this bound in check

.route("/upload/:output_format", post(handler_convert_file));
| ---- ^^^^^^^^^^^^^^^^^^^^ the trait Handler<_, _> is not implemented for fn item fn(Path<String>, Multipart) -> impl Future<Output = ...> {handler_convert_file}

`

[wangziling]

Hi Vitaliy~ After pulling your demo codes.

I found that maybe you missing to impl IntoResponse for your DownloadFile struct in src/web/routes_files.rs :12.

impl IntoResponse for DownloadFile {
    fn into_response(self) -> axum::response::Response {
        use axum::http::HeaderValue;

        let mut res = self.file_data.0.into_response();
        res.headers_mut().insert(
            "content-disposition",
            // File name.
            HeaderValue::from_bytes(self.file_name.as_bytes()).unwrap(),
        );

        res
    }
}

And your handler_convert_file method has two ways to fix the errors.

1. Remove the Ok() wrapper.'Cause the compiler didn't know What the Error is when you are using the std::result::Result<T, Error>::Ok(), you didn't point it out.
   

2. Using the Result what is made alias by yourself.

Result::Ok(build_response_file)

Or just modify the method's return type.

And then you need to impl IntoResponse trait for customized Error enum.

[wangziling]

If you want to make sure to catch all the errors in handler_convert_file method.

Suggests that you'd better to remove all the maybe-panic .unwrap() invokings, just using the ? operation.
And then you need enhance the Error handling events.
https://github.com/rust-lang/crates.io/blob/main/src/util/errors.rs I'm following the crates.io's error handling events.

[Lucky-49]

Thank you very much for your detailed answer!!! You helped solve my problem!