I'm not sure what you're looking for--you can write custom Java validators in S2, or use the validate() method. If you have complicated logic that needs to return to a page other than the INPUT result it'll require more work.
Joined: Aug 10, 2006
I guess I am looking for a way to implement custom validation that will be inspected at the same time as annotation and xml-validator validation.
the validate() method runs at a different priority from my experience.
Then you'd implement a custom validator, much the same way as in S1. It might be more straight-forward to implement it in a validate() method, however.
As far as the different "priority", just like with S1, you can call super.validate() inside the validate() method, so that the DB-based validation is run immediately after the XML/annotation-based validation, which I'd assume is what you'd want anyway.