yii\mongodb\file\Download::getDocument PHP Method

    public function getDocument()
    {
        if (!is_array($this->_document)) {
            if (is_scalar($this->_document) || $this->_document instanceof ObjectID) {
                $document = $this->collection->findOne(['_id' => $this->_document]);
                if (empty($document)) {
                    throw new InvalidConfigException('Document id=' . $this->_document . ' does not exist at collection "' . $this->collection->getFullName() . '"');
                }
                $this->_document = $document;
            } else {
                $this->_document = (array) $this->_document;
            }
        }
        return $this->_document;
    }