I am developing a user authentication system with expressjs. Therefore to store user data i use a mysql database... When I query to my database I do it with this: SELECT password FROM USERS WHERE email=EmailHere
The problem with this is I dont know an elegant solution to returning an error message if the email doesnt exist. Somewhat understandable?
So to conclude: I want to know if that value exists when I query to the db so I dont get an error message.
Edit:
const query = `SELECT password FROM USERS WHERE email=?;`;
let [rows, fields] = await db.promise().query(query, [req.body.email]);
const password = rows[0].password;
console.log(password);
This gives me the error: Cannot read properties of undefined reading 'password'.
So it is trying to access the .password column. Can I prevent that?
Thanks in advance! Have a great day
Ok it turns out:
If I check if the length of the rows Array > 0 it fixes the problem. In the else statement I can just log out an error message to say the user does not exist. This could look something like this:
if (!rows.length > 0) return res.status(400).send('User doensnt exist!');
const password = rows[0].password;
// Declaring the variable after I know it exists.
Thanks to @danblack for this answer!
try to change the query like that
SELECT password FROM USERS WHERE email like '%';
or
SELECT password FROM USERS WHERE email='%';
please if you find it a solution don't forget to mark it as answer .