public function placeholderCallback($matches) { // Only sections defined in the event can be referenced if (!GenericSectionUpdater::isSectionBeingEvaluated($matches[1])) { return $matches[0]; } // System:id links if ($matches[2] == 'system:id') { if (isset($_POST[$matches[1]]['system:id'])) { return $_POST[$matches[1]]['system:id']; } $replacement_key = '{@system-id:' . $matches[1] . '@}'; self::$temporary_unreolved_links[] = array('target-handle' => $matches[1], 'field-name' => $matches[2], 'replacement-key' => $replacement_key); return $replacement_key; } return $_POST[$matches[1]][$matches[2]]; }