Sending streams as response

Hi there,

Is it possible to send streams somehow? Roughly, I’m trying to do this:

@Get("/*")
public async processRequest(@Req() request, @Res() response) {
        ...
        const readableStream = await myStorage.getBlobAsStream();
        readableStream.pipe(response);
       ...
}

…and receive the error like this:

Application has thrown an uncaught exception and is terminated:
Error [ERR_STREAM_WRITE_AFTER_END]: write after end
    at write_ (_http_outgoing.js:572:17)
    at ServerResponse.write (_http_outgoing.js:567:10)
    at RetriableReadableStream.ondata (_stream_readable.js:666:20)
    at RetriableReadableStream.emit (events.js:182:13)
    at RetriableReadableStream.Readable.read (_stream_readable.js:486:10)
    at flow (_stream_readable.js:922:34)
    at resume_ (_stream_readable.js:904:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)

Could you please advise?

[wsmd]

Hey all - routing-controllers does support returning streams directly from a controller method (via https://github.com/typestack/routing-controllers/pull/285), but I’ve found it a bit tricky at first when it comes to piping streams (i.e. readable.pipe(response)).

I’ve managed to get piping streams to work by using either of the two following methods:

1. Piping the readable to the response and returning a Promise

@Get('/pipe_with_promise')
promise(@Res() res: Response) {
  return new Promise<Response>((resolve, reject) => {
    const readable = getReadableStreamSomehow();
    readable.pipe(res);
    readable.on('end', () => resolve(res));
    readable.on('error', (error) => reject(error));
  });
}

2. Piping the readable to a PassThrough stream and returning it

import { PassThrough } from 'stream';

// ...

@Get('/pipe_with_passthrough')
passthrough() {
  const stream = new PassThrough();
  getReadableStreamSomehow().pipe(stream);
  return stream;
}

Note that with the Passthrough approach, I’ve encountered some issues with the content-type not being inferred automatically, so you may need to use @ContentType as well, depending on your use case.

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