Tracking model changes in after_commit :on => :create callback

You can't use the rails changed? method, as it will always return false. To track changes after the transaction is committed, use the previous_changes method. It will return a hash with attribute name as key. You can can then check if your attribute_name is in the hash:

after_commit :foo

def foo
 if previous_changes[attribute_name]
   #do your task
 end
end