Promise still go to the next chain after I return res.end()

Question

I'm using bluebird in node with express ,when I return res.end(),Promise still goes to the next chain,here's my code:

Promise.resolve(operate).then(function(data){
    if (!!data && data.length !=0) {
        log.info('success');
        return true;
    }else {
        log.warn('fail');
        return res.end();
    }
}).then(function(data){
    if(data) {
        log.info('done');
        return res.end();
    }else {
        log.warn('fail');
        return res.end();
    }
})

And I got 2 'fail' in the log if it's failed,how can i make it stop if i got 'fail' in the first time?Thank you!

bluebird version:~2.10.2; node: 4.3.1; express:~4.2.0

Answer 1

You can return either an error or a rejected promise instead of res.end. This will skip all success handlers until the end of the promise chain (technically until the first rejection handler):

Promise.resolve()
  .then(() => Promise.reject())
  .then(
     () => console.log('this does not run'), // <-- success handler
     () => console.log('this runs')          // <-- rejection handler
  );

So in your code:

Promise.resolve(operate).then(function(data){
  if (!!data && data.length !=0) {
    log.info('success');
    return true;
  } else {
    log.warn('fail');
    res.end();
    return Promise.reject(/* optionally pass an error */); // <--- return rejected promise
  }
}).then(function(data){
  // this won't run if previous promise rejects
})