How can I implement async validation in Joi?

How can I implement async validation in Joi?

You can implement async validation in Joi by using the Joi.extend() method to create a custom validation rule.

Can you show me an example of that?

Sure! Here's a simple example:

const Joi = require('joi');

const schema = Joi.object({
  email: Joi.string().email().custom(async (value, helpers) => {
    const isTaken = await checkEmailInDatabase(value);
    if (isTaken) {
      return helpers.error('any.invalid');
    }
    return value;
  })
});

What does checkEmailInDatabase do?

checkEmailInDatabase is a hypothetical function that checks if the email already exists in your database. You would need to implement that function to perform the actual database query.