express form validation code example

Example 1: express validator

// this method create custom express validator using middleware

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

exports.resultsValidator = (req) => {
  const messages = []
  if (!validationResult(req).isEmpty()) {
    const errors = validationResult(req).array()
    for (const i of errors) {
      messages.push(i)
    }
  }
  return messages
}

exports.registerValidator = () => {
  return [
    check('username')
      .notEmpty()
      .withMessage('username is required')
      .not()
      .custom((val) => /[^A-za-z0-9\s]/g.test(val))
      .withMessage('Username not use uniq characters'),
    check('password')
      .notEmpty()
      .withMessage('password is required')
      .isLength({ min: 8 })
      .withMessage('password must be 8 characters')
  ]
}

exports.loginValidator = () => {
  return [
    check('username').notEmpty().withMessage('username or email is required'),
    check('password').notEmpty().withMessage('password is required')
  ]
}

// how to use express validator in controller for results message
const errors = resultsValidator(req)
  if (errors.length > 0) {
    return res.status(400).json({
      method: req.method,
      status: res.statusCode,
      error: errors
    })
  }

// how to use express validator in route
route.post('/login', loginValidator(), (req, res) => {
   return res.status(200).send('Login Sucessfuly');
});

route.post('/register', registerValidator(), (req, res) => {
   return res.status(200).send('Register Sucessfuly');
});

Example 2: express validator

npm install --save express-validator

Example 3: express-validator

// ...rest of the initial code omitted for simplicity.
const { body, validationResult } = require('express-validator');

app.post('/user', [
  // username must be an email
  body('username').isEmail(),
  // password must be at least 5 chars long
  body('password').isLength({ min: 5 })
], (req, res) => {
  // Finds the validation errors in this request and wraps them in an object with handy functions
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(422).json({ errors: errors.array() });
  }

  User.create({
    username: req.body.username,
    password: req.body.password
  }).then(user => res.json(user));
});