Run a callback only if an attribute has changed in Rails

Question

I have the following association in my app:

# Page 
belongs_to :status

I want to run a callback anytime the status_id of a

Answer 1

Try this

after_validation :do_something, if: ->(obj){ obj.status_id.present? and obj.status_id_changed? } 

def do_something
 # your code
end

Reference - http://apidock.com/rails/ActiveRecord/Dirty