Or no table changes with http://api.rubyonrails.org/classes/ActiveRecord/Locking/Pess...

but in this specific case `affected_rows` works better as long as you know its reliable.

Right, but that involves changing your database and adding hidden form fields to your app in order for it to work on a multi process environment (like every production server should be.)

My solution is basically the same amount of lines, requires no such changes.

Yes, but optimistic locking with a version is the general and known solution to this problem in all cases and is built into the framework already. Your solution works in just one case, not the general case.