PHP DynamoDB Poll using Zend Framework 2

gistfile1.php

<?php

namespace Application\Controller;

use Aws\DynamoDb\DynamoDbClient;
use Aws\DynamoDb\Enum\ComparisonOperator;
use Aws\DynamoDb\Enum\Type;
use Zend\Mvc\Controller\AbstractActionController;
use Zend\View\Model\JsonModel;
use Zend\View\Model\ViewModel;

class IndexController extends AbstractActionController
{

    private $table_name = "shoppers_btr_poll";

    private $client;

    public function indexAction()
    {
        return new ViewModel();
    }


    public function dynamoTestAction()
    {
        $sm = $this->getServiceLocator();
        $aws = $sm->get('aws');

        /** @var DynamoDbClient $client */
        $this->client = $aws->get('dynamodb');

        $this->vote( 1 );

        $response = $this->getPollAnswers( 1, 4 );

        return new JsonModel( $response );
    }

    private function getPollAnswers( $min, $max )
    {
        $response = $this->client->scan( array(
            'TableName' => $this->table_name,
            'ScanFilter' => array(
                'poll_id' => array(
                    'ComparisonOperator' => ComparisonOperator::BETWEEN,
                    'AttributeValueList' => array(
                        array( Type::NUMBER => $min ),
                        array( Type::NUMBER => $max ),
                    ),
                ),
            ),
        ));

        $poll = array();
        foreach( $response['Items'] as $x )
            $poll[$x['poll_id'][Type::NUMBER]] = $x['votes'][Type::NUMBER];

        ksort( $poll );
        return $poll;
    }


    private function vote( $poll_id )
    {
        $this->client->updateItem( array(
            'TableName' => $this->table_name,
            'Key' => array(
                'poll_id' => array( Type::NUMBER => $poll_id )
            ),
            'AttributeUpdates' => array(
                'votes' => array(
                    'Action' => 'ADD',
                    'Value' => array(
                        Type::NUMBER => 1
                    ),
                ),
            ),
        ));

    }

}