Is it possible to know what exactly changed using an observer in ruby on rails?

Question

I need send an email alert when the price of a product changes. Is it possible do this with ActiveRecord::Observer or do I need use programming logic in the edit form?

Answer 1

You can use Dirty Objects in order to achieve that, in this specific case, you'll have something like this in your observer.

FooMailer.deliver_alert(foo) if foo.price_changed?

According to: "Once you save a dirty object it clears out its changed state tracking and is once again considered unchanged" You should ask for the prince_changed? before the save operation is done.

Hope It helps you.