Express-validator check if email existed with MySQL - mysql

Question

Im using express-validator to check if the req.body entered is valid and to check if there is duplicate email in the MySQL database
Here is my code:
router.post(
"/signup",
[
body("uemail","email is not valid")
.isEmail()
.normalizeEmail()
.custom(async (email, {req} )=>{
const queryString = "SELECT uid FROM EarlyUsers WHERE `uemail` = ?";
return await connection.query(queryString, [email], (err, rows, fields) => {
if (err) {
console.log(err)
}else {
if (rows.length != 0) {
return false
} else {
return true
}
}
});
})
,
body("uname").isLength({ min: 5 })
],
authControllers.signUp
);
I dont know why this custom validator does not work.
I've tried to throw new Error instead of return false, but it just crash the whole thing . I really need help with this

Answer 1

For it to work correctly instead of returning false you reject the Promise.
if (rows.length != 0) {
return Promise.reject("user already exists.");
}

Answer 2

I have achieved this way it might be helpful for others, I'm using sequelize :)
const User = require("../../models/User");
body('email', 'Invalid email').exists().isEmail().trim().escape().custom(userEmail=> {
return new Promise((resolve, reject) => {
User.findOne({ where: { email: userEmail } })
.then(emailExist => {
if(emailExist !== null){
reject(new Error('Email already exists.'))
}else{
resolve(true)
}
})
})
}),

Answer 3

I found this solution to check that the email is not duplicate:
router.post('/register',
body('email').isEmail().normalizeEmail().withMessage('The email format is not correct.').custom((email) => {
const queryString = `SELECT * FROM users WHERE user_email = "${email}"`;
return getFinalEmail(queryString).then(user => {
console.log(user);
if (user) {
return Promise.reject('E-mail already in use');
}
});
}),
// -- other validations
// .....
(req, res) => {
/* your code for this route */
}); // end of router('/register')
function getFinalEmail(param) {
return new Promise(function(resolve, reject) {
getEmailData(param, function(result) {
console.log(result);
resolve(result);
});
});
}
function getEmailData(query, callback) {
database.query(query, function(error, data){
if(data.length > 0) {
return callback(true);
} else {
return callback(false);
}
});
}
In the above code users is the name of my table and user_email is the column that email data of users are stored.