Validation callback

In my head this makes sense, as the form validation is checking the data received is in the format I expected, the further checks like is the password current, or is the code matched to a discount structure or whatever, has nothing to do with if the data is of the right form or not. It is almost as if we are trying to do too much business logic within a simple form validation. I expect 8 chars, I get 8 chars, validation passed. Whether those eight chars are matched to anything, or if they serve a particular business logic requirement or not, is not really anything to do with form input validation. I know people will have different opinions on this, just my humble opinion.

I made this for less request for mysql (check password). If you typing small password I can't request to database for in vain.

I still have problem.
I want get callback with other validations, or this impossible?