How "equals" in express-validator works? - express

Question

I have to validate two fields are equals. In this case both passwords are the same. The problem it is that the "equals" from express-validator is not working.
This is the code:
app.post('/register', [
isNotLogged,
check('email', 'The email must be a valid one').isEmail(),
check('nickname', 'The nickname must be filled').notEmpty(),
check('password', 'The password must contain minimum eight characters, at least one letter and one number')
.matches("^(?=.*[A-Za-z])(?=.*\\d)[A-Za-z\\d]{8,}$"),
//This is not working
check('passwordConfirm', 'The passwords must match').equals('password'),
validateResults
], register)

Answer 1

Unfortunately Express-Validator doesn't work with Validator.js's equals(), you'll have to use one of Express-Validator's middlewares and not its Validator.js affility.
Here is an example straight from Express-Validator's website which seems fit your use case:
body('oldPassword')
// if the new password is provided...
.if((value, { req }) => req.body.newPassword)
// OR
.if(body('newPassword').exists())
// ...then the old password must be too...
.notEmpty()
// ...and they must not be equal.
.custom((value, { req }) => value !== req.body.newPassword);
You do not need to use Express-Validator's check middleware as you are throwing away your ability to utilise Validator.js's validators. Instead of check you could use isEmail() and exists() (an Express-Validator validator). Also, you don't need to have your middlewares as part of an array (although you can):
app.post('/register',
isNotLogged,
body('email').isEmail().withMessage('The email must be a valid one').bail().trim(),
body('nickname').exists({ checkNull: true }).withMessage('The nickname must be filled').bail().trim(),
body('password').trim().if((value, { req }) => (typeof req.body.passwordConfirm !== 'undefined')).bail().custom((value, { req }) => value !== req.body.passwordConfirm).withMessage('The email must be a valid one').bail().trim().matches("^(?=.*[A-Za-z])(?=.*\\d)[A-Za-z\\d]{8,}$"),
validateResults,
register
);
Here the body() function would come from const { body } = require('express-validator') theres a few others similar for query paramaters, header parameters ect, all are documented here.
I also used some trim()s and bails()s just to be safe. You can read up on those here and here.

Answer 2

I solve this problem like this:
code before:
const registrar = async (req, res) => {
await check('password').isLength({ min:6}).withMessage('password short ').run(req);
await check('repetir_password').equals('password').withMessage('password diferente?').run(req);
let resultado = validationResult(req);
res.json(resultado.array());
};
after:
correct code: change
'password'
by
req.body.password
const registrar = async (req, res) => {
await check('password').isLength({ min: 6 }).withMessage('password corta ').run(req);
await check('repetir_password').equals(req.body.password).withMessage('password diferente?').run(req);
let resultado = validationResult(req);
res.json(resultado.array());
};