How to Async Mongoose Controller - node.js

Question

Trying to configure a SignUp() controller that can update multiple (separate) user accounts when a referral code is provided by the user.
Basic Flow:
Verify email doesn't already exist in system
Find the driver w/ userID matching the rider's refCode (FindOneAndUpdate)
If Found: Add the userID of each user to the other users [clients] list
Only need to do a refCode match if isRider
If any of those fail... Return the specific error to the client/user
This does not work. But essentially, this is what I'm trying to accomplish...
// POST `/signup` (Create a new local user)
export function signUp(req, res, next) {
const newUser = new User({
email: req.body.email,
password: req.body.password,
profile: {
userID: req.body.userID,
refCode: req.body.refCode,
isRider: req.body.isRider
}
});
User.findOne({ email: req.body.email }, (findErr, foundUser) => {
if (foundUser) {
return res.status(409).send('This e-mail address already exists');
}
// riders must link to a driver
if (req.body.isRider) {
// find driver + add rider ID to clients
return User.findOneAndUpdate({ 'profile.userID': req.body.refCode }, { $push: { clients: newUser.profile.userID }}).exec()
.then((err, foundDriver) => {
if (err) {
return res.status(409).send('Error searching for driver');
} else if (!foundDriver) {
return res.status(409).send(`We can't find your driver (${req.body.refCode})!`);
}
// add driver ID to rider's clients
newUser.clients = [req.body.refCode];
return newUser.save((saveErr) => {
if (saveErr) return next(saveErr);
return req.logIn(newUser, (loginErr) => {
if (loginErr) return res.sendStatus(401);
return res.json(newUser.profile);
});
});
});
}
return newUser.save((saveErr) => {
if (saveErr) return next(saveErr);
return req.logIn(newUser, (loginErr) => {
if (loginErr) return res.sendStatus(401);
return res.json(newUser.profile);
});
});
});
}
Tried to configure it as a pure promise but no luck. Most of the examples out there all seem different to me... Also could not figure out how to handle/throw specific errors using the mongoose docs.
Greatly appreciated if anyone can lend a hand, Thx!
UPDATE:
Ippi's answer helped a ton - Thx!
This does the trick. Remember to return null from .then() after the req.login stuff to avoid warnings - Any tips on how to improve this are appreciated - Thx!
const createUser = (foundUser) => {
if (foundUser) { throw new Error('This e-mail address already exist.'); }
if (!req.body.isRider) { return newUser.save(); }
return User.findOneAndUpdate({ 'profile.userID': req.body.refCode.toLowerCase() }, { $push: { clients: newUser.profile.userID }}).exec()
.then((driver) => {
if (!driver) { throw new Error('We can\'t find your driver.'); }
newUser.clients = [req.body.refCode];
return newUser.save();
})
.catch(() => { throw new Error('There was a database error.'); });
};
User.findOne({ email: req.body.email }).exec()
.then(createUser)
.then((user) => {
if (user.profile) {
req.logIn(user, (loginErr) => {
if (loginErr) return res.sendStatus(401);
return res.status(200).send({ profile: user.profile, clients: user.clients });
});
} else { res.status(409); }
return null;
})
.catch((err) => { return res.status(409).send(err.message); });

Answer 1

function signUp(req, res, next) {
return new Promise((resolve, reject) => {
const newUser = new User({
email: req.body.email,
password: req.body.password,
profile: {
userID: req.body.userID,
refCode: req.body.refCode,
isRider: req.body.isRider
}
});
User.findOne({ email: req.body.email }, (findErr, foundUser) => {
if (foundUser) {
// return res.status(409).send('This e-mail address already exists');
reject('This e-mail address already exists');
}
// riders must link to a driver
if (req.body.isRider) {
// find driver + add rider ID clients
return User.findOneAndUpdate({ 'profile.userID': req.body.refCode }, { $push: { clients: newUser.profile.userID } }).exec()
.then((err, foundDriver) => {
if (err) {
// return res.status(409).send('Error searching for driver');
reject('Error searching for driver');
} else if (!foundDriver) {
// return res.status(409).send(`We can't find your driver (${req.body.refCode})!`);
reject(`We can't find your driver (${req.body.refCode})!`);
}
// add driver ID to rider's clients
newUser.clients = [req.body.refCode];
newUser.save((saveErr) => {
if (saveErr)
// next(saveErr);
reject(saveErr);
req.logIn(newUser, (loginErr) => {
if (loginErr)
// return res.sendStatus(401);
reject('401');
// return res.json(newUser.profile);
resolve(newUser.profile);
});
});
});
}
newUser.save((saveErr) => {
if (saveErr)
// return next(saveErr);
reject(saveErr);
req.logIn(newUser, (loginErr) => {
if (loginErr)
// return res.sendStatus(401);
reject(loginErr);
// return res.json(newUser.profile);
resolve(newUser.profile);
});
});
});
});}

Answer 2

This is how I would do it. I couldn't be bothered to try with express or the login (you need to replace console.log with res.status().json()) and I might have done some other blunder in the logic with the driver. But other than that I tested it with local mongo and it probably works and if nothing else it's a little bit more concise.
let updateUser = user => {
if (user){ throw new Error("USER_EXIST"); }
if (!req.body.isRider) { return newUser.save() }
return User.findOneAndUpdate({ 'profile.userID': req.body.refCode },{ $push: { clients: newUser.profile.userID }}).exec()
.then(driver => {
if (!driver) { throw new Error("NO_DRIVER");}
newUser.clients.push(req.body.refCode);
return newUser.save();
});
}
User.findOne({ email: req.body.email }).exec()
.then(updateUser)
.then(req.logIn) // newUser.save() response is passed in as is (I have not tested this line.)
.then( ()=>{ return console.log('profile', newUser.profile); })
.catch( Error, err => {
if (err.message == "USER_EXISTS") return console.log ("This e-mail address already exist." );
if (err.message == "NO_DRIVER") return console.log ("We can't find your driver." );
throw err;
});
Something worth remembering:
Callback calls or res.send should always go in the last then / catch. Calling res.send in middle of chains leads to trouble.