node.js – How to add Express-Validator checks inside other middleware?

Question:

I'm using Express-Validator to validate the data that the user enters.

router.post('/register', [check('email').not().isEmpty().withMessage('Enter an email.'), check('password', 'The password must be at least 6 characters').not().isEmpty()], checkData, registerPostRoute);

However, I think it's too polluted to put all these checks in there, before the next middleware. On the other hand, I can't pass these checks into the checkData middleware so the code looks just like this:

router.post('/register', checkData, registerPostRoute);

I don't know if I'm doing it correctly, but does anyone know if it's possible to pass these checks into the checkData middleware?

Answer:

Yes, it is possible. One way I do in my projects is to organize the validation middlewares in a dedicated file just for that.

Here is a suggestion for organizing the validation middlewares:

login.validator.js

const { body, validationResult } = require('express-validator');

exports.validationBodyRules = [
    body('login', 'login is required').exists(),
    body('password', 'password is required').exists(),
    body('login', 'login is required').notEmpty(),
    body('password', 'password is required').notEmpty()
];

exports.checkRules = (req, res, next) => {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
        return res.status(400).json({ errors: errors.array() });
    }
    next();
};

In this example I make use of the body validation function. In your case, just keep using check .

It is also necessary to use the validationResult function, it will serve to raise error messages and stop the chaining of middlewares, in this case I am launching status-code 400 (this is an implementation detail, but it is possible to launch its status-code defined in the story provided for this feature).

After creating the validation middleware, just use it in the route you want, as follows:

route.js

const router = require('express').Router();
const loginService = require('../controllers/login.controller');
const loginValidator = require('../validators/login.validator');

router.post('/login', loginValidator.validationBodyRules, loginValidator.checkRules, loginService.logEmployee);

module.exports = router;

This is an example of organization I use in my projects, which is also the way of implementation recommended by the express-validator documentation .