after_commit and after_destroy callbacks are not called on ActiveRecord::Relation delete_by method

Question

I am using ActiveRecord::Relation delete_by method to delete a record but this is not triggering after_commit and after_destroy callbacks. See below example:

class User < ActiveRecord::Base
  after_commit :expire_cache
  after_destroy :expire_cache

  def expire_cache
    puts "expire_cache is called"
  end
end

User.delete_by(user_id: 1234) # doesn't trigger expire_cache method

Is my expectation about the callbacks is right? What am I doing wrong?

Answer 1

Is my expectation about the callbacks is right?

No. Your expectation to trigger a callback with delete_by is wrong.

What am I doing wrong?

Your understanding is not matching with doc.

As per the Doc, skipping-callbacks delete_all will skip the callbacks

• delete_all Just as with validations, it is also possible to skip callbacks.

• These methods should be used with caution, however, because important business rules and application logic may be kept in callbacks. Bypassing them without understanding the potential implications may lead to invalid data.

Answer 2

If you want your callbacks to run, use destroy_by instead:

User.destroy_by(id: 1234)

These methods were introduced in Rails 6. More info here:

• https://blog.saeloun.com/2019/10/15/rails-6-delete-by-destroy-by.html
• https://github.com/rails/rails/issues/35304

Knowing the differences between delete and destroy also helps: Difference between Destroy and Delete