The Mongoid::Attributes.attribute_present? method reads the attribute then returns value.blank? This is not a correct implementation for boolean values. The blank? method returns true if a boolean value is false. Thus, attribute_present? incorrectly returns false for boolean values that are present but false.

This implementation is a copy of the ActiveRecord.attribute_present? method, for which I have also submitted a bug here:

https://github.com/rails/rails/issues/1613