How can I validate route parameters in Express?

How can I validate route parameters in Express?

You can use middleware to validate route parameters in Express. Libraries like Joi or express-validator are popular choices.

Can you show me an example using express-validator?

Sure! First, install express-validator. Then, you can use it like this:

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

app.get('/user/:id', [
  param('id').isInt(),
], (req, res) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ errors: errors.array() });
  }
  res.send('User ID is valid!');
});

What if the parameter is not valid?

If the parameter is not valid, the middleware will catch the error and return a 400 status with the error details.