# response to http://www.davidverhasselt.com/set-attributes-in-activerecord/#comment-1663663372
# just remember that this code requires you to either use super or attr_name_will_change! in your overridden setters and getters
# @see http://api.rubyonrails.org/classes/ActiveModel/Dirty.html
def update_attribute_without_other_attributes(name, value)
  # get all changed values (self.changes returns hash with [ old_value, new_value ] or nil as values, we only want new_value)
  changes_before = self.changes.inject({}) { |h, (k,v)| h[k] = (v.respond_to?(:last) ? v.last : v); h }
  changes_before.delete name
  restore_attributes # reset_changes for Rails 4.1

  save_result = update_attribute(name, value)
  # restore changes
  attributes(changes_before)
  save_result
end