public function insertComboSet($comboset) {
        global $wpdb;

        $wpdb->query('START TRANSACTION');
        $cs = (new REST\ComboSet())->create(['skuMetaId' => $comboset['skuMetaId']], $comboset);
        if ($cs instanceof GenericError) {
            return;
        }
        foreach ($comboset['groups'] as $group) {
            $gres = (new REST\ComboGroup())->create(['comboSetId' => $cs->getId()], $group);
            if ($gres instanceof GenericError) {
                $wpdb->query('ROLLBACK');
                return;
            }

            foreach ($group['items'] as $item) {
                if (empty($item['skucode']) || empty($item['postId'])) {
                    continue;
                }
                $sku = wel_get_sku($item['postId'], $item['skucode']);
                if (empty($sku)) {
                    continue;
                }

                $res = (new REST\GroupItem())->create(
                    ['groupId' => $gres->getId()],
                    array_merge($item, ['welitemSkuMetaId' => $sku['meta_id']])
                );
                if ($res instanceof GenericError) {
                    $wpdb->query('ROLLBACK');
                    return;
                }
            }
        }
        $wpdb->query('COMMIT');
    }