    # File lib/active_record/base.rb, line 2491
          def cache_key
            case
            when new_record?
              "#{self.class.model_name.cache_key}/new"
            when timestamp = self[:updated_at]
              "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}"
            else
              "#{self.class.model_name.cache_key}/#{id}"
            end
          end