code: public function init()
      {
          parent::init();
  
          if (empty($this->attributes)) {
              $this->attributes = [BaseActiveRecord::EVENT_BEFORE_VALIDATE => $this->slugAttribute];
          }
  
          if ($this->attribute === null && $this->value === null) {
              throw new InvalidConfigException('Either "attribute" or "value" property must be specified.');
          }
      }
docs: {@inheritdoc}