Illuminate\Database\Eloquent\Model::saveOrFail PHP Method

    public function saveOrFail(array $options = [])
    {
        return $this->getConnection()->transaction(function () use($options) {
            return $this->save($options);
        });
    }

 /**
  * @param Model $user
  *
  * @return string
  */
 public function encode(Model $user)
 {
     /** @var User $user */
     $secret = str_random();
     $token = json_encode([self::KEY_USER_ID => $user->getKey(), self::KEY_SECRET => $secret]);
     $user->{User::FIELD_API_TOKEN} = $secret;
     $user->saveOrFail();
     return $token;
 }