/**
  * @return \yii\db\ActiveQuery
  */
 public function getUploads()
 {
     if (is_null($this->files)) {
         $this->files = UploadedFile::getFilesByCollectionId($this->id);
     }
     return $this->files;
 }
 public function saveFields($fieldsNamesArray)
 {
     $toUpdate = [];
     foreach ($fieldsNamesArray as $field) {
         $collection = $this->behavior->owner->{$field};
         if (!is_null($collection)) {
             $collection->save();
             UploadedFile::saveNewFilesFromCollection($collection);
             $toUpdate[$field] = (int) $collection->id;
         }
     }
     $this->behavior->owner->updateAttributes($toUpdate);
 }