Using ActiveRecord, is there a way to get the old values of a record during after_update

Question

Setup using a simple example: I\'ve got 1 table (Totals) that holds the sum of the amount column of each record in a second table (

Answer 1

Some other folks are mentioning wrapping all this in a transaction, but I think that's done for you; you just need to trigger the rollback by raising an exception for errors in the after_* callbacks.

See http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html

The entire callback chain of a save, save!, or destroy call runs within a transaction. That includes after_* hooks. If everything goes fine a COMMIT is executed once the chain has been completed.

If a before_* callback cancels the action a ROLLBACK is issued. You can also trigger a ROLLBACK raising an exception in any of the callbacks, including after_* hooks. Note, however, that in that case the client needs to be aware of it because an ordinary save will raise such exception instead of quietly returning false.