public function filterVariants()
 {
     if (!$this->owner->isNewRecord) {
         if (is_array($this->filterVariants)) {
             return $this->filterVariants;
         }
         $values = FilterValue::findAll(['item_id' => $this->owner->id]);
         $this->filterVariants = [];
         foreach ($values as $value) {
             $this->filterVariants[$value->variant_id] = $value->variant_id;
         }
         return $this->filterVariants;
     } else {
         return [];
     }
 }