Rails 3: How to identify after_commit action in observers? (create/update/destroy)

Question

I have an observer and I register an after_commit callback. How can I tell whether it was fired after create or update? I can tell an item was destroyed by asking

Answer 1

Take a look at the test code: https://github.com/rails/rails/blob/master/activerecord/test/cases/transaction_callbacks_test.rb

There you can find:

after_commit(:on => :create)
after_commit(:on => :update)
after_commit(:on => :destroy)

and

after_rollback(:on => :create)
after_rollback(:on => :update)
after_rollback(:on => :destroy)

Answer 2

I've learned today that you can do something like this:

after_commit :do_something, :on => :create

after_commit :do_something, :on => :update

Where do_something is the callback method you want to call on certain actions.

If you want to call the same callback for update and create, but not destroy, you can also use: after_commit :do_something, :if => :persisted?

It's really not documented well and I had a hard time Googling it. Luckily, I know a few brilliant people. Hope it helps!

Answer 3

Based on leenasn idea, I created some modules that makes it possible to use after_commit_on_updateand after_commit_on_create callbacks: https://gist.github.com/2392664

Usage:

class User < ActiveRecord::Base
  include AfterCommitCallbacks
  after_commit_on_create :foo

  def foo
    puts "foo"
  end
end

class UserObserver < ActiveRecord::Observer
  def after_commit_on_create(user)
    puts "foo"
  end
end