How can I customize error messages in Express Validator?

How can I customize error messages in Express Validator?

You can customize error messages in Express Validator by using the withMessage method in your validation chain.

Can you show me an example of how to do that?

Sure! Here's a simple example:

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

app.post('/user', [
  body('email').isEmail().withMessage('Please enter a valid email address.'),
  body('password').isLength({ min: 5 }).withMessage('Password must be at least 5 characters long.')
], (req, res) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ errors: errors.array() });
  }
  // Proceed with user creation
});

What if I want to customize the error messages based on the field?

You can customize messages for each field by chaining the withMessage method to each validation rule, as shown in the example.