How to convert node read stream to observable RX

Question

If I have a Node js stream, say, for example, from something like process.stdinor from fs.createReadStream, how can I convert this as an RxJs Observable stream using RxJs5?

I see that RxJs-Node has a method fromReadableStream, but it seems that it has not been updated in close to a year.

Answer 1

For those who are looking for this, following Mark's recommendation, I adapted the rx-node implementation fromStreamfor rxjs5 .

import { Observable } from 'rxjs';

// Adapted from https://github.com/Reactive-Extensions/rx-node/blob/87589c07be626c32c842bdafa782fca5924e749c/index.js#L52
export default function fromStream(stream, finishEventName = 'end', dataEventName = 'data') {
  stream.pause();

  return new Observable((observer) => {
    function dataHandler(data) {
      observer.next(data);
    }

    function errorHandler(err) {
      observer.error(err);
    }

    function endHandler() {
      observer.complete();
    }

    stream.addListener(dataEventName, dataHandler);
    stream.addListener('error', errorHandler);
    stream.addListener(finishEventName, endHandler);

    stream.resume();

    return () => {
      stream.removeListener(dataEventName, dataHandler);
      stream.removeListener('error', errorHandler);
      stream.removeListener(finishEventName, endHandler);
    };
  }).share();
}

Answer 2

The following should work for both v4 and v5 (disclaimer):

fromStream: function (stream, finishEventName, dataEventName) {
    stream.pause();

    finishEventName || (finishEventName = 'end');
    dataEventName || (dataEventName = 'data');

    return Observable.create(function (observer) {

      // This is the "next" event
      const data$ = Observable.fromEvent(stream, dataEventName);

      // Map this into an error event
      const error$ = Observable.fromEvent(stream, 'error')
        .flatMap(err => Observable.throw(err));

      // Shut down the stream
      const complete$ = Observable.fromEvent(stream, finishEventName);

      // Put it all together and subscribe
      const sub = data$
        .merge(error$)
        .takeUntil(complete$)
        .subscribe(observer);

      // Start the underlying node stream
      stream.resume();

      // Return a handle to destroy the stream
      return sub;
    })

    // Avoid recreating the stream on duplicate subscriptions
    .share();
  },

Answer 3

RxJs- Node RxJs4, RxJs5 https://github.com/Reactive-Extensions/rx-node/blob/87589c07be626c32c842bdafa782fca5924e749c/index.js#L52