Bitmask attributes are not reset when an object is reloaded

[sferik]

Unlike normal attributes, unsaved bitmask attributes are not reset when an object is reloaded. This was very surprising to me!

def test_bitmask_attributes_reload
  user = User.create(:name => "Bruce", :roles => [:publisher, :editor])

  # Normal attribute behavior
  assert_equal "Bruce", user.name
  user.name = "Erik"
  assert_equal "Erik", user.name
  user.reload
  assert_equal "Bruce", user.name

  # Bitmask attribute behavior (very surprising!)
  assert_equal [:publisher, :editor], user.roles
  user.roles << :writer
  assert_equal [:publisher, :editor, :writer], user.roles
  user.reload
  assert_equal [:publisher, :editor], user.roles
  #1) Failure:
  # <[:publisher, :editor]> expected but was
  # <[:publisher, :editor, :writer]>.
end

[spemmons]

I've found the same problem and have constructed a test for it to add to the project that will currently fail:

      should "update bitmask values currently in the database with reload" do
        instance1 = @campaign_class.create(:medium => [:web, :print])
        instance2 = @campaign_class.find(instance1.id)
        assert instance1.id == instance2.id
        assert instance1.object_id != instance2.object_id
        assert instance1.update_attributes(:medium => [:email])

        assert_equal [:web, :print],instance2.medium

        instance2.reload
        assert_equal [:email],instance2.medium
      end

However, I'm not sure what the fix is. In reviewing the AR code, there doesn't appear to be a clear way to detect this situation and refresh the ValueProxy objects used to cache the current set of symbols corresponding to the integer values of the model.

Any suggestions?

[spemmons]

So, to answer my own question: We could simply overload the "reload()" method for the model. That *should be okay. I'll work up a proposed solution and submit...

[justqyx]

Hi @spemmons @sferik

I found it is not compatible with activerecord 4.2.7.1. and it should overwrite the reload method in the included block like this.

included do
  alias_method :reload_without_bitmasks, :reload
  def reload(options = nil)
    super_result = reload_without_bitmasks(options)
    self.class.bitmasks.keys.each { |attribute| send("reload_#{attribute}") }
    super_result
  end
end

And I think it should be auto included by ActiveRecord::Base, it should be included by explicit declaration as follow

class Example < ActiveRecord::Base
  extend BitmaskAttributes
  # ...
end