With this tutorial there are in total four different approaches described for doing data validation with CakePHP:
- The official approach described in the manual
- Complex Model Validation Routines
- Advanced validation
- Alternate Advanced Validation
Which one you use is up to you and your requirements ;-)
Update (2008-08-12): Fixing broken links. Please be aware that most of those validation approaches are quite old and it is possible they no longer work.