protected function from_db_records(array $results) : array {
        $entityfactory = $this->get_entity_factory();

        return array_map(function(array $result) use ($entityfactory) {
            [
                'forum' => $forumrecord,
                'course_module' => $coursemodule,
                'course' => $course,
                'context' => $context,
            ] = $result;
            return $entityfactory->get_forum_from_stdclass($forumrecord, $context, $coursemodule, $course);
        }, $results);
    }