Question

I have a Rails model class like this:

class Something < ActiveRecord::Base

  before_create do
     self.key = SecureRandom.urlsafe_base64(8)
  end

end

Why can I call before_create here? I expected it to be a method of ActiveRecord::Base but it is not. Callbacks are methods of ActiveRecord::Callbacks. But why can I call them in a model class without including something?

Answer 1

You can do that because ActiveRecord::Base does this (or something similar depending on your version of Rails):

Base.class_eval do
  #...
  include Callbacks, ActiveModel::Observing, Timestamp
  #...
end

So ActiveRecord::Base already includes ActiveRecord::Callbacks and your class picks up the callbacks by inheriting from ActiveRecord::Base.