express check required fields code example

Example 1: 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));
});

Example 2: example of validating fields on your own in express

const User = require('./models/user')

exports.createUser = (req, res, next) => {
  /** Here you need to validate user input. 
   Let's say only Name and email are required field
 */
  
  const { userName, email, phone, status } = req.body
  if (userName && email &&  isValidEmail(email)) { 
    
    // isValidEmail is some custom email function to validate email which you might need write on your own or use npm module
    User.create({
      userName,
      email,
      phone,
      status,   
    })
    .then(user => res.json(user))
    .catch(next)
  }
}