previous_record_id

# File activerecord/lib/active_record/associations/belongs_to_association.rb, line 81
        def previous_record_id
          @previous_record_id ||= if @reflection.options[:primary_key]
                                    previous_record = @owner.send(@reflection.name)
                                    previous_record.nil? ? nil : previous_record.id
                                  else
                                    @owner[@reflection.primary_key_name]
                                  end
        end