Callbacks order in Rails

Question

If I have code in my model file like this:

after_destroy :method_1
after_destroy :method_2

Do method_1 and method_2 execute together or method_1 first then method_2? Does it make a difference if I do:

after_destroy :method_1, method_2

A reference to the documentation would be great. thanks

Answer 1

ActiveRecord::Callbacks documents the order in "Ordering callbacks". The order changed subtly in Rails 7.1.

Rails 7.1 and newer

All callbacks are executed in the order they are defined.

class Topic < ActiveRecord::Base
  after_save :log_children
  after_save :do_something_else

  ...
end

When a Topic is saved, log_children will be executed, then do_something_else.

Prior to Rails 7.1

Before Rails 7.1, transactional callbacks (after_commit, after_rollback) do the opposite; the last defined transactional callback is executed first.

class Topic < ActiveRecord::Base
  after_commit :log_children
  after_commit :do_something_else

  ...
end

When a Topic is committed, first do_something_else runs, then log_children.

If there's any doubt, you can combine them into a single callback.

class Topic < ActiveRecord::Base
  after_commit :commit_callback

  private def commit_callback
    log_children
    do_something_else
  end

  ...
end

If you're upgrading Rails you can maintain compatibility by setting

config.active_record.run_after_transaction_callbacks_in_order_defined = false

See Active Record Callbacks - 11.3 Transactional Callback Ordering