express-validator wrong check

Question

I'm using express-validator 5.3.1. I defined password check like this :

check('password')
  .not().isEmpty().withMessage('Password can\'t be null')
  .isString()
  .isLength({ min: 8 }),
check('retypePassword')
  .not().isEmpty().withMessage('Password can\'t be null')
  .isString().withMessage('Password must be a string')
  .custom((value, { req }) => {
    if(value.trim() !== req.body.password.trim()) {
      throw new Error ('Password confirmation does not match password');
    }
  }),

For testing, I send same password and retypePassword ('password') and got error :

[ { "location": "body", "param": "retypePassword", "value": "password", "msg": "Invalid value" } ]

I defined message with all error of retypePassword, so what's going on ?

Answer 1

When you implement a custom validation you have to return true if the validation succeed, otherwise you will get the "Invalid value" error message. So you just add a return true; statement like this

.custom((value, { req }) => {
    if(value.trim() !== req.body.password.trim()) {
        throw new Error ('Password confirmation does not match password');
    }
    return true;
})