Getting Parameter when Form_for is Submitted

This is slightly tied with my previous post. I wasn't sure if I was
supposed to make another message in there, so I made a new post.

So in my previous post I accidentally asked a pure ruby question about
gsub which I'll be using in this question.

Anyways, what I want to do is to take a single parameter from user's
input in the Form_for and run it through the gsub code [ @file_cut =
order.gsub(/[\w ! # $ % ^ & * + -]+\.doc$/, '*.doc) ] when the user
submits the form. The parameter will still be stored in the database
so I don't think test_field_tag, etc. will help me unless you think
otherwise. Also, I'm hoping not to use javascript in my code.

Here's my code:

orders_controller.rb

Problem solve. Just did multiple redirects.