Hello mate ! Sorry for the late answer, I was on a business trip in Paris.
You can do whatever suits you but here is two remarks:
1/ It is hard for me to give you a straight answer, because I don't know what "id_cat" refers too (what is it ?), and I don't why you can't give a proper name to your fields (I don't know why you don't do "id_cat_something", "id_cat_something_else"...). I am sure there is a reason, but I don't know which one :-)
2/ Personally, I use helpers when I need it (at least) in more than one page (more than one time). But maybe you don't want to have php in your html template (which is understandable).
