+ $keypart = sprintf('rsvp:for-event:%s', $event->id);
+
+ $idstr = self::cacheGet($keypart);
+
+ if ($idstr !== false) {
+ $ids = explode(',', $idstr);
+ } else {
+ $ids = array();
+
+ $rsvp = new RSVP();
+
+ $rsvp->selectAdd();
+ $rsvp->selectAdd('id');
+
+ $rsvp->event_id = $event->id;
+
+ if ($rsvp->find()) {
+ while ($rsvp->fetch()) {
+ $ids[] = $rsvp->id;
+ }
+ }
+ self::cacheSet($keypart, implode(',', $ids));
+ }
+