Validating email and username in clean style - node.js

Question

I need to validate a username (if one is provided) and an email (if one is provided) before saving to the db. I'm using MongooseJS, However, I'm not sure how to structure my code
Here is what I have so far:
var user = new User();
if(req.body.email) {
User.findOne({"email" : req.body.email}, function(err, found){
if(err) return next(err);
if(found) return res.status(200).send({"error_code" : "INVALID_REQUEST_ERROR", "message" : "Email address already exists"});
});
}
if(req.body.username) {
User.findOne({"username" : req.body.username}, function(err, found){
if(err) return next(err);
if(found) return res.status(200).send({"error_code" : "INVALID_REQUEST_ERROR", "message" : "Username already exists"});
});
}
user.save(function(err){
if(err) return next(err);
res.status(200).send(user);
});
but of course this won't work as the user.save will be executed before either of the validation blocks execute. I realise I could put user.save inside the callbacks but then I would be repeating code which I want to avoid.

Answer 1

The best thing to do is to add validation on to your mongoose Schema and let it do it automatically whenever you attempt to save a model (or you can call the validation function yourself earlier). Like so:
var userSchema = new Schema({
email: {
type: String,
required: true,
validate: {
validator: function(v) {
var emailRegexp = /^[-a-z0-9~!$%^&*_=+}{\'?]+(\.[-a-z0-9~!$%^&*_=+}{\'?]+)*#([a-z0-9_][-a-z0-9_]*(\.[-a-z0-9_]+)*\.(aero|arpa|biz|com|coop|edu|gov|info|int|mil|museum|name|net|org|pro|travel|mobi|[a-z][a-z])|([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}))(:[0-9]{1,5})?$/i;
return emailRegexp.test(v);
},
message: "{VALUE} does not appear to be a valid email address."
}
}
});
Then when you try to save it with incorrect data:
var user = new User({ email: "this_isnt_a_proper_email" });
user.save(function(err) {
if (err.name === "ValidationError") { // check that it comes from mongoose validation
console.log(err.errors.email.message)
res.status(400).send({ validationError: err }); // send "Bad Request" HTTP header
} else {
res.send(user) // status 200 is implicit when not set
}
});
To better organise the code that checks whether the username or email is already set in the database, I'd suggest looking up Bluebird (or similar) Promises, so that you can have a logical flow to the process.

Answer 2

Another simple way maybe
var user = new User();
var email = req.body.email || '';
var username = req.body.username || '';
User.find({
$or: [{"email": email}, {"username": username}]},
function(err, users){
if(err) return next(err);
if(users && users.length == 0) {
// save new user if none is matched
user.save(function(err){
if(err) return next(err);
res.status(200).send(user);
});
} else if (users && users.length > 0) {
// check users returned to determine which of following two error codes should be returned
//return res.status(200).send({"error_code" : "INVALID_REQUEST_ERROR", "message" : "Email address already exists"});
//return res.status(200).send({"error_code" : "INVALID_REQUEST_ERROR", "message" : "Username already exists"});
}
});
You could do it through Promise, here is one sample codes by using Q.js
function findUserByEmail() {
var deferred = Q.defer();
if(req.body.email) {
User.findOne({"email" : req.body.email}, function(err, found){
if(err) return deferred.reject(err);
if(found) {
res.status(200).send({"error_code" : "INVALID_REQUEST_ERROR", "message" : "Email address already exists"});
deferred.reject();
}else {
// no user is found, resolve it
deferred.resolve();
}
});
} else {
deferred.reject();
}
return deferred.promise;
}
function findUserByName() {
var deferred = Q.defer();
if(req.body.username) {
User.findOne({"username" : req.body.username}, function(err, found){
if(err) return deferred.reject(err);
if(found) {
res.status(200).send({"error_code" : "INVALID_REQUEST_ERROR", "message" : "Username already exists"});
deferred.reject();
} else {
// no user is found, resolve it
deferred.resolve();
}
});
} else {
deferred.reject();
}
return deferred.promise;
}
Q.all([findUserByName(), findUserByEmail()]).then (function() {
// in the resolve function, namely, no exist username and email
user.save(function(err){
if(err) return next(err);
res.status(200).send(user);
});
});