the trait bound `s3::request::ResponseDataStream: tokio::io::AsyncRead` is not satisfied

[frederikhors]

I'm having really hard time both with 0.32 and 0.33 beta when I need to get an tokio::io::AsyncRead + Send type in return.

I found out this extremely useful doc to convert tokio <-> futures: https://github.com/benkay86/async-applied/blob/master/reqwest-tokio-compat/src/main.rs but I cannot apply it here.

I'm using the code below:

impl Trait for Client {
    async fn get_file(&self, filename: &str) -> Result<Pin<Box<dyn tokio::io::AsyncRead + Send>>> {
        let file = self.bucket.get_object_stream(filename).await?;

        Ok(Box::pin(file))
    }
}

but it errors with:

error[E0277]: the trait bound `s3::request::ResponseDataStream: tokio::io::AsyncRead` is not satisfied
   |
59 |         Ok(Box::pin(file))
   |            ^^^^^^^^^^^^^^ the trait `tokio::io::AsyncRead` is not implemented for `s3::request::ResponseDataStream`
   |
   = help: the following other types implement trait `tokio::io::AsyncRead`:
             &[u8]
             &mut T
             h2::codec::framed_write::FramedWrite<T, B>
             hyper::server::tcp::addr_stream::AddrStream
             hyper::upgrade::Upgraded
             hyper_tls::stream::MaybeHttpsStream<T>
             reqwest::async_impl::upgrade::Upgraded
             sqlx_core::net::socket::Socket
           and 26 others
   = note: required for the cast from `s3::request::ResponseDataStream` to the object type `dyn tokio::io::AsyncRead + std::marker::Send`

Can you help me fix this, please?

[durch]

Hi @frederikhors, I'd suggest using tokio::fs::file to open the file, and pass it in. Apologies for the trouble, docs have rotted a bit since 0.32, this used to be much better documented

[frederikhors]

I'm not opening a file...

[durch]

I'm not opening a file...

Sorry got confused, when I saw the method name up there, get_object_stream will return a ResponseDataStream, ResponseDataStream in turn has the bytes method which returns a &mut Pin<Box<dyn Stream<Item = Bytes>>>, that might get you closer to what you need

[frederikhors]

We have chosen to use other methods. Thank anyway.