public function get_guide_filling($force = false) {
        global $DB;
        if ($this->guide === null || $force) {
            $records = $DB->get_records('gradingform_guide_fillings', array('instanceid' => $this->get_id()));
            $this->guide = array('criteria' => array());
            foreach ($records as $record) {
                $record->score = (float)$record->score; // Strip trailing 0.
                $this->guide['criteria'][$record->criterionid] = (array)$record;
            }
        }
        return $this->guide;
    }