|string> */ public function rules(): array { return [ 'url' => 'required|string', 'description' => 'required|string', 'user_id' => 'required|exists:users,id', 'course_id' => 'required|exists:courses,id', 'course_forum_id' => 'required|exists:course_forums,id', 'course_forum_user_id' => 'required|exists:users,id', ]; } }