Warp

[ronanyeah]

Is it possible to pass the output of this warp filter to multer?
https://docs.rs/warp/0.3.1/warp/filters/body/fn.stream.html

I can't get it to work.

async fn handler<S, B>(form: S) -> Result<impl warp::Reply, warp::Rejection>
where
    S: Stream<Item = Result<B, warp::Error>>,
    S: StreamExt,
    B: warp::Buf,
{

From what I can gather, warp::Buf needs to satisfy Into<Bytes>?

[rousan]

@SergioBenitez

[SergioBenitez]

Yes, but it's not clear to me from warp's sparse documentation how to do so efficiently and correctly. The gist is that you need to convert the impl Buf (note that Buf is a trait, not a concrete type) into something that implements Into<Bytes>. Here are some ideas:

• Map the stream into a stream of Bytes using copy_to_bytes on the impl Buf.
• Use the bytes filter instead of stream.
• The use form filter instead of multer.

All of these do much more copying and allocating than one would hope, but it's not clear to be that warp allows anything better.

[ronanyeah]

I got #2 working, thanks a lot to both of you. Here's the code:

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let env = envy::from_env::<Env>().expect("Missing environment variables!");

    let routes = warp::post()
        .and(warp::path("new-listing"))
        .and(warp::filters::header::value("Content-Type"))
        .and(warp::filters::body::bytes())
        .and_then(handle_form);

    warp::serve(routes).run(([0, 0, 0, 0], env.port)).await;

    Ok(())
}

async fn handle_form(
    content_type: warp::http::header::HeaderValue,
    form: bytes::Bytes,
) -> Result<impl warp::Reply, warp::Rejection> {
    let stream = futures::stream::once(async move { Result::<bytes::Bytes, Infallible>::Ok(form) });

    let boundary = multer::parse_boundary(content_type.to_str().unwrap()).unwrap();

    let mut multipart = multer::Multipart::new(stream, boundary);

    while let Some(field) = multipart.next_field().await.unwrap() {
        println!("Field: {:?}", field.text().await)
    }

    let response = serde_json::json!({ "message": "OK" });
    Ok(warp::reply::json(&response))
}