How can I use async validators with express-validator?

How can I use async validators with express-validator?

You can use async validators in express-validator by utilizing the async keyword in your validation functions. This allows you to perform asynchronous operations, like checking a database for existing values.

Can you give me an example of an async validator?

Sure! Here's a simple example:

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

const checkEmailExists = async (email) => {
    const user = await User.findOne({ email });
    if (user) {
        throw new Error('Email already in use');
    }
};

app.post('/register', [
    body('email').isEmail().custom(checkEmailExists)
]);

What happens if the async validator fails?

If the async validator fails, it will throw an error, and express-validator will handle it by returning a 400 response with the error message.

Can I use multiple async validators?

Yes, you can chain multiple async validators by using the .custom() method for each one. Just ensure they return promises.