delete_records

# File activerecord/lib/active_record/associations/has_many_through_association.rb, line 126
        def delete_records(records, method)
          ensure_not_nested

          scope = through_association.scoped.where(construct_join_attributes(*records))

          case method
          when :destroy
            count = scope.destroy_all.length
          when :nullify
            count = scope.update_all(source_reflection.foreign_key => nil)
          else
            count = scope.delete_all
          end

          delete_through_records(records)

          if source_reflection.options[:counter_cache]
            counter = source_reflection.counter_cache_column
            klass.decrement_counter counter, records.map(&:id)
          end

          if through_reflection.macro == :has_many && update_through_counter?(method)
            update_counter(-count, through_reflection)
          end

          update_counter(-count)
        end