Doctrine\ODM\MongoDB\Query\Builder::setDocumentName PHP Method

    private function setDocumentName($documentName)
    {
        if (is_array($documentName)) {
            $documentNames = $documentName;
            $documentName = $documentNames[0];

            $discriminatorField = $this->dm->getClassMetadata($documentName)->discriminatorField['name'];
            $discriminatorValues = $this->getDiscriminatorValues($documentNames);
            $this->field($discriminatorField)->in($discriminatorValues);
        }

        if ($documentName !== null) {
            $this->collection = $this->dm->getDocumentCollection($documentName);
            $this->database = $this->collection->getDatabase();
            $this->class = $this->dm->getClassMetadata($documentName);
        }
    }