If you have a model that is using single table inheritance, the simple
new, create, edit, and update methods and views might not do what you
want them to do. I have an ActiveRecord::Base with just a name and a
type so I can define a Team (type) of “account” and a Dept of Education.
But suppose I misspell Education and I want to edit it. What happens is
the edit method finds the record and makes it into a Dept (type or
class). This confuses the form_for(@name) into producing URLs for Dept
which in my case isn’t want I wanted. I wanted to edit the entry as a
name. (In my case, I don’t have URLs and controllers for Team or Dept,
The solution was to us becomes(klass) so the edit method becomes:
@name = Name.find(params[:id]).becomes(Name)
I did that same thing after all of the calls to find in this case.
There are probably 99% of the time that you want find to change the
instance into the proper class but if you don’t, this is a simple way to
cast it back to the parent class.