public function favourite_exists(string $component, string $itemtype, int $itemid, \context $context) : bool {
        return $this->repo->exists_by(
            [
                'userid' => $this->userid,
                'component' => $component,
                'itemtype' => $itemtype,
                'itemid' => $itemid,
                'contextid' => $context->id
            ]
        );
    }