Newbie question about .titlecase of .titleize


i just started to work with ROR, and made a form with scaffolding.
I achieved to add some extra inputvalidation but i also want to add some
code that changes some specific textfields with the .titlecase /
.titleize and then stores it to the database.

I had to add the validation code to the model file, is this also the
place to add the titlecase ?
the columname of the regarding textfield is last_name(db)/lastname(ror)