yii\mongodb\file\Upload::init PHP Метод

    public function init()
    {
        $this->hashContext = hash_init('md5');
        if (isset($this->document['_id'])) {
            $this->documentId = $this->document['_id'] instanceof ObjectID ? $this->document['_id'] : ObjectID($this->document['_id']);
        } else {
            $this->documentId = new ObjectID();
        }
        $this->collection->ensureIndexes();
    }