How can I create custom validations using express-validator?

How can I create custom validations using express-validator?

You can create custom validations in express-validator by using the custom method. Would you like an example?

Yes, please provide an example of a custom validation.

Sure! Here's a simple example:

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

app.post('/user', [
  body('email').custom(value => {
    if (!isValidEmail(value)) {
      throw new Error('Invalid email format');
    }
    return true;
  })
]);

This checks if the email is valid using a custom function.

What if I want to validate multiple fields?

You can chain multiple validations together. For example:

app.post('/user', [
  body('email').isEmail().withMessage('Must be a valid email'),
  body('password').isLength({ min: 5 }).withMessage('Password must be at least 5 characters long')
]);