Custom extractor for Multipart

[barvirm]

Summary

Hello, can I write custom extractor for Multipart forms? I tried something like this, but I'm afraid it might not be possible due to the lifetime of multipart.

struct StreamedFile {
    filename: String,
    fieldname: String,
    content_type: String,
    stream: Pin<Box<dyn Stream<Item = Result<Bytes, MultipartError>> + Send>>,
}

#[async_trait]
impl<S> FromRequest<S> for StreamedFile
where
    S: Send + Sync,
{
    type Rejection = (StatusCode, String);

    async fn from_request(request: Request, state: &S) -> Result<Self, Self::Rejection> {
        // Create the multipart object from the request
        let Ok(mut multipart) = Multipart::from_request(request, state).await else {
            return Err((StatusCode::BAD_REQUEST, "Expect Multipart form with ...".into()));
        };

        let field = match multipart.next_field().await {
            Ok(Some(field)) => field,
            Ok(None) => return Err((StatusCode::BAD_REQUEST, "Missing multipart field".into())),
            Err(error) => return Err((error.status(), error.body_text())),
        };

        let fieldname = field
            .name()
            .map(|v| v.to_string())
            .ok_or((StatusCode::BAD_REQUEST, "I don't care".into()))?;

        let filename = field.file_name().map(|v| v.to_string()).ok_or((
            StatusCode::BAD_REQUEST,
            "Missing filename annotation for file field".into(),
        ))?;

        let content_type = field.content_type().unwrap_or("application/octet-stream").to_string();

        let stream = field.into_stream().boxed();

        Ok(StreamedFile {
            fieldname,
            filename,
            content_type,
            stream,
        })
    }
}

axum version

0.7.7