delete_records

# File activerecord/lib/active_record/associations/has_many_association.rb, line 70
        def delete_records(records)
          case @reflection.options[:dependent]
            when :destroy
              records.each { |r| r.destroy }
            when :delete_all
              @reflection.klass.delete(records.map { |record| record.id })
            else
              relation = Arel::Table.new(@reflection.table_name)
              relation.where(relation[@reflection.primary_key_name].eq(@owner.id).
                  and(relation[@reflection.klass.primary_key].in(records.map { |r| r.id }))
              ).update(relation[@reflection.primary_key_name] => nil)

              @owner.class.update_counters(@owner.id, cached_counter_attribute_name => -records.size) if has_cached_counter?
          end
        end