public function createService(ServiceLocatorInterface $serviceLocator)
    {
        $config = $serviceLocator->get('config')['mongoObjectMapper'];
        $client = self::constructMongoClient(@$config['uri'], @$config['options']);

        $mapperClass = 'MongoObject\Mapper';
        if (isset($config['mapperClass'])) {
            $mapperClass = $config['mapperClass'];
        }

        return new $mapperClass($client->selectDb($config['database']), @$config['modelsNamespace']);
    }