public function find($user_id): ?User
    {
        return app('cache.array')->rememberForever(__CLASS__ . $user_id, static function () use ($user_id): ?User {
            return DB::table('user')
                ->where('user_id', '=', $user_id)
                ->get()
                ->map(User::rowMapper())
                ->first();
        });
    }