Problem Statement

Based on this example from Rails: https://guides.rubyonrails.org/active_record_callbacks.html#transaction-callbacks
 

class Picture < ApplicationRecord
  after_commit :delete_picture_file_from_disk, on: :destroy

  def delete_picture_file_from_disk
    File.delete(filepath) if File.exist?(filepath)
  end
end

This callback will only be triggered if the Picture object is deleted within a transaction.

If you add an additional after_destroy callback, then destroying within a transaction will trigger the delete_picture_file_from_disk method twice: once when destroy is called, and once again on commit. A further problem is that, if the transaction is rolled back, then the after_destroy would have still been called.

What makes the most sense for users is to have a callback method that is guaranteed to trigger only once immediately after the persistence action has happened, either on commit (if transaction) or else after a normal op (if non-transaction).

Proposed Solutions

Possible solutions could be:
1. Introduce a new after_persistence callback, which has the behavior described above.
2. Alter the behavior of the existing callbacks after_commit and/or after_save. This is probably undesirable as it would create divergence from Rails.