- $action = ($event_id == '') ? 'new' : "event/" . $event_id;
- $onerror_path = "events/" . $action . "?summary=$summary&description=$desc&location=$location&start=$start_text&finish=$finish_text&adjust=$adjust&nofinish=$nofinish";
+ $params = [
+ 'summary' => $summary,
+ 'description' => $desc,
+ 'location' => $location,
+ 'start' => $start_text,
+ 'finish' => $finish_text,
+ 'adjust' => $adjust,
+ 'nofinish' => $nofinish,
+ ];
+
+ $action = ($event_id == '') ? 'new' : 'event/' . $event_id;
+ $onerror_path = 'events/' . $action . '?' . http_build_query($params, null, null, PHP_QUERY_RFC3986);