I'm trying to chain a second then method after the first one but it's not working correctly for some reason. It only works fine when I'm nesting the then method. Here's the code that doesn't work correctly:
auth.post('/signup', (req, res, next) => {
const { username } = req.body
const { password } = req.body
Users.findOne({ username })
.then(
existingUser => {
if (existingUser) return res.status(422).send({ error: 'Username is in use' })
const user = new Users({ username, password })
user.save()
},
err => next(err)
)
.then(
savedUser => res.send({
username: savedUser.username,
password: savedUser.password
}),
err => next(err)
)
})
Here when I post to '/signup'
user
gets saved into the database but I don't get the response with username and password. However:
auth.post('/signup', (req, res, next) => {
const { username } = req.body
const { password } = req.body
Users.findOne({ username })
.then(
existingUser => {
if (existingUser) return res.status(422).send({ error: 'Username is in use' })
const user = new Users({ username, password })
user.save()
.then(
savedUser => res.json({
username: savedUser.username,
password: savedUser.password
}),
err => next(err)
)
},
err => next(err)
)
})
This works as expected. user
gets saved and I get the response with username and password. I've read that you can chain these then methods in a flat way without nesting. But I've checked questions on here and couldn't find an answer as to what I'm doing wrong here. Can someone please help with this issue?
You have at least three issues with your "chained" version
.then
.then
would still be executedUsers.findOne
the chained .then
would also be executedTo fix:
.save()
Promise.reject
- alternatively you can throw
an erroronRejected
functions in .then
, just have a single rejection handler, at the end of the chain, in a .catch
I would chain that code like this:
auth.post('/signup', (req, res, next) => {
const { username } = req.body
const { password } = req.body
Users.findOne({ username })
.then(existingUser => {
if (existingUser) {
return Promise.reject({
status:422,
error: 'Username is in use'
});
}
return new Users({ username, password }).save();
})
.then(savedUser => res.send({
username: savedUser.username,
password: savedUser.password
}))
.catch(err => {
if (err.status) {
return res.status(err.status).send({ error: err.error });
}
return next(err);
});
});