Catch errors in promise if promise returned and forward them to error handling middleware

[meghprkh]

Currently, Express forwards errors thrown in a route using throw and forwards them to error handling middleware. But it doesnot do something similar if a promise is returned. I have to manually append .catch(next) to the promise to get it forwarded to error handling middleware. For example the following is my code:

// errorHandlers.js
function sequelizeValidationError (err, req, res, next) {
  if (err.name && err.name == 'SequelizeValidationError')
    res.status(400).send(err.errors)
  else next(err)
}

// auth.js
router.post ('/register',  middleware.isNotAuthenticated, (req, res, next) => {
  const { email, password, name } = req.body;

  return models.User.find({where : { email }}).then(user => {
    if (user) {
      if (user.password == password) sendToken(user.id, res);
      else res.sendStatus(401);
    } else {
      return models.User.create({
        email, password, name
      }).then(user => {
        sendToken(user.id, res);
      })
    }
  }).catch(next)
})

// index.js
router.use('/auth', require('./auth'))

router.use(errorHandlers.sequelizeValidationError)

It currently fails if I had to forgot to write the catch, instead of automatically calling the error handling middleware. This can result to errors if I somewhere fail to write catch andd IMHO it is inconsistent too.

Also a small question, can I make a middleware to handle this case temporarily? (sorry I know I shouldnt ask this but please)

[blakeembrey]

This is a duplicate of #3029, #3026 and #2259. I would follow #2259 for more information. To fix this today, you can wrap it in something like https://github.com/blakeembrey/async-middleware.