Callback for changed ActiveRecord attributes?

Question

I am aware of ActiveRecord::Dirty and the related methods, but I don\'t see a means by which I can subscribe to an attribute changed event. Something like:

Answer 1

The easiest way that I found:

after_save :my_method, :if => Proc.new{ self.my_attribute_changed? }

def my_method
  ... do stuff...
end