Editing POST info before adding to the DB

Hello, I have a script that parses a CSV during POST and pops the data into my MySQL db. It works great, but I want to edit some info from the CSV before I put it into the DB. In my case, I need to strip off the leading number off of strings are 11 characters in length. I was recommended that I do this in the model... I'm not exactly sure how to do this... What I have is this in my model:

class Bes < ActiveRecord::Base   def besnumber      if bes.bes_phonenumber.to_s.size == 11         bes.bes_phonenumber = bes.bes_phonenumber.to_s.slice(1..11)            end   end end

However, after I upload it and check the database, the numbers haven't been cut. How exactly does this MVC work? I mean, does it go from the index view to the model then to the controller? Wouldn't I then want to put this in the controller? I am very new to RoR and any help is appreciated!

Thanks, - Jeff Miller