    public function __construct($mongo, array $options)
    {
        if (!($mongo instanceof \MongoClient || $mongo instanceof \Mongo)) {
            throw new \InvalidArgumentException('MongoClient or Mongo instance required');
        }

        if (!isset($options['database']) || !isset($options['collection'])) {
            throw new \InvalidArgumentException('You must provide the "database" and "collection" option for MongoDBSessionHandler');
        }

        $this->mongo = $mongo;

        $this->options = array_merge(array(
            'id_field' => '_id',
            'data_field' => 'data',
            'time_field' => 'time',
            'expiry_field' => 'expires_at',
        ), $options);
    }
The software constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component.