I would like to have a synchronized query in JavaScript to check it query's response before doing anything else. I can not insert the rest of my code into the processing of the query because I would like to return a status code when an error appears.
I tried to put the rest of code into the query treatment but I got this message on my terminal : Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
router.post('/login', (req, res) => {
const { error } = validate(req.body);
if(error) return res.status(400).send(error.details[0].message);
const queryString = `SELECT * FROM user_admin WHERE email = '${req.body.email}' AND password = '${req.body.password}'`;
connection.query(queryString, (err, rows) => {
console.log(rows);
if(err) throw err;
else if(rows.length != 0){
res.status(200).json({
'token': jwtUtils.generateTokenForUser(rows[0].iduser_admin)
});
}
return res.status(404).send('ERROR 404 : Password and (or) email are false.');
});
});
This is my actual code :
router.post('/login', (req, res) => {
const { error } = validate(req.body);
if(error) return res.status(400).send(error.details[0].message);
var iduser_admin = findUserId();
if(iduser_admin === 0 || iduser_admin === undefined) return res.status(404).send('ERROR 404 : Password and (or) email are false.');
res.status(200).json({
'token': jwtUtils.generateTokenForUser(iduser_admin)
});
});
function findUserId(){
const queryString = `SELECT * FROM user_admin WHERE email = '${req.body.email}' AND password = '${req.body.password}'`;
connection.query(queryString, (err, rows) => {
console.log(rows);
if(err) throw err;
else if(rows.length != 0){
return rows[0].iduser_admin;
}
return 0;
});
}
Since JS is asynchronous, my variable isadmin_user is not updated before the next if. So, it's always status (400).
I don't find how to use .then() or callback in this case. (I'm new with JS)
Because if I put the rest of code inside an other function called by my query treatment the problems with res.status will appear, no ? Could you help me ?
