Allow resolving promise with stream

[analog-nico]

Request-Promise is not designed to be used with streams. However, Request-Promise could resolve the promise not with the response but with the stream object. Then the user could do some piping further down the promise chain.

See request/request#1990 which gave me the idea.

At community: +1s?

[analog-nico]

This wouldn't be possible currently in conjunction with the simple option because Request-Promise would need to register .on('response', ... ) to get and check the statusCode. But then all .pipe(...) calls need to follow synchronously - which is not the case due to the async hop of the promise. (See the linked issue.)

[analog-nico]

It turns out to be possible after all by pausing the stream during the async step:

new Promise(function(resolve, reject) {
    request.get('http://affenbits.com/')
        .on('response', function(response) {
            response.pause();
            resolve(response);  
        });
}).then(function(response) {
    response.pipe(process.stdout);
});

[simov]

That's good, you can probably use additional pause option to enable that behavior? Also not sure if .on vs .one would make any difference in this case.

[analog-nico]

A pause option would be neat. Although the solution above works well without the option, in the future the option could give request the power to pause the stream "at the right time". Who knows, maybe some cases come up where the response event it not "the right time".

[sabrehagen]

+1

[forivall]

wip / sample: https://gist.github.com/forivall/6b3f3718b5684e9ea8daa5a4dcd855a6

I'll turn that into a pull request if nobody else is working on this.

[analog-nico]

Hi @forivall , a PR would be really awesome!

You'll need to add the changes to request-promise-core. This core lib is used by request-promise, request-promise-native, and request-promise-any. But anyhow, the change won't require specific code for any one of those libs...

[sabrehagen]

@forivall Thank you for your work. Eagerly awaiting your pull request!