The SitePoint PHP blog has posted a tutorial showing you how to validate your data with Respect (well, their validation library) and ensure the data you're getting is exactly what you're expecting.

Validation is an important aspect of every application’s interaction with data. Instead of reinventing the wheel every time, the community collaborated on some useful packages like Symfony, Laravel, Zend, etc. In this article, we’re going to introduce a lesser known package called Respect Validation, which provides some nice new features.

He starts by mentioning some of the other popular validation packages used widely in the PHP community including the Symfony Validator and Laravel's Illuminate package. For each of these he shows code validating an email address, each with their own slight differences. Using this same example he shows how to implement it in the Respect library, first making use of their custom "email" validator class then via custom chained rules. He also shows how to set custom error messages and provides a more "real world" example with a simple Laravel application. His application takes in user data including username, password and credit card information and uses Respect's library to validate it via a full set of rules. He ends the post with a quick look at creating your own custom rule classes and how to "cross pollinate" them with Zend or Symfony validators.