Zend Framework 2 : Using Zend\Cache and HydratingResultSet to Save Database Resultset into Cache

Re-load data from the database every web was accessed is not good for your server ‘health’. Zend Framework has a component named Hydrator. The Hydrator is a simple component to provide mechanisms both for hydrating objects, as well as extracting data sets from them.
To save database ResultSet into cache, You need to use Zend\Db\ResultSet\HydratingResultSet which can extract the resultSet into associative array. In this post, i will show you how to cache your database resultset into filesystem.

Let’s code :
1. Register Zend\Cache\Storage\Filesystem into service manager. You can place it at global.php

return array(
    'db' => array(/*common code*/),
    'service_manager' => array(
        'factories' => array(
            'Zend\Db\Adapter\Adapter' => 'Zend\Db\Adapter\AdapterServiceFactory',
            'Zend\Cache\Storage\Filesystem' => function($sm){
		    $cache = Zend\Cache\StorageFactory::factory(array(
			'adapter' => 'filesystem',
			'plugins' => array(
			    'exception_handler' => array('throw_exceptions' => false),
			    'serializer'
			)
		    ));
		    
		    $cache->setOptions(array(
			    'cache_dir' => './data/cache'
		    ));
                    
                    return $cache;
	    },
        ),
    ),
);

2. Define Your Sample class

namespace SampleModule\Model;

use Zend\InputFilter\Factory as InputFactory;
use Zend\InputFilter\InputFilter;
use Zend\InputFilter\InputFilterAwareInterface;
use Zend\InputFilter\InputFilterInterface;

class Sample implements InputFilterAwareInterface
{
    public $id;
    public $name;
    public $gender;
    
    protected $inputFilter;

    public function exchangeArray($data)
    {
        $this->id     = (isset($data['id'])) ? $data['id'] : null;
        $this->name = (isset($data['name'])) ? $data['name'] : null;
        $this->gender = (isset($data['gender'])) ? $data['gender'] : null;
    }
    
   public function getArrayCopy()
    {
        return get_object_vars($this);
    } 
    
    public function setInputFilter(InputFilterInterface $inputFilter)
    {
        throw new \Exception("Not used");
    }
    
    public function getInputFilter()
    {
        /* common code here */
        return $this->inputFilter;
    }
}

3. next, create your Sample table class :

namespace SampleModule\Model;

use Zend\Db\Adapter\Adapter;
use Zend\Db\ResultSet\HydratingResultSet;
use Zend\Db\TableGateway\AbstractTableGateway;
use Zend\Db\Sql\Select;

use Zend\Cache\Storage\StorageInterface;

class SampleTable extends AbstractTableGateway
{
    protected $table = 'sampletable';
    protected $cache;
    
    public function __construct(Adapter $adapter)
    {
        $this->adapter = $adapter;
        $this->resultSetPrototype = new HydratingResultSet();
        $this->resultSetPrototype->setObjectPrototype(new Sample());
        
        $this->initialize();
    }
    
    public function setCache(StorageInterface $cache)
    {
        $this->cache = $cache;
    } 
    
    public function fetchAll()
    {   
        if( ($resultSet = $this->cache->getItem('samplecache')) == FALSE) {
           
            $resultSet = $this->select(function (Select $select){
                $select->columns(array('id', 'name', 'gender'));
                $select->order(array('id asc'));  
            });

            $resultSet = $resultSet->toArray();
            $this->cache->setItem('samplecache',  $resultSet );
        }
 
        return $resultSet;
    }
}

4. Last step, register Zend\Cache in Module.php to inject cache into Sample Table Class.

namespace SampleModule;

use Zend\ModuleManager\Feature\AutoloaderProviderInterface;
use Zend\ModuleManager\Feature\ConfigProviderInterface;
use Zend\ModuleManager\Feature\ServiceProviderInterface;

class Module  implements
    AutoloaderProviderInterface,
    ConfigProviderInterface,
    ServiceProviderInterface
{
    public function getAutoloaderConfig(){/*common code*/}
    public function getConfig(){/*common code*/}
    
    public function getServiceConfig()
    {
	return array(
	    'factories' => array(
                'SampleModule\Model\SampleTable' =>  function($sm){
                    $dbAdapter    = $sm->get('Zend\Db\Adapter\Adapter');
		    $cacheAdapter = $sm->get('Zend\Cache\Storage\Filesystem');
		    
                    $table     = new Model\SampleTable($dbAdapter);
		    $table->setCache($cacheAdapter);
		    
                    return $table;
                },
            ),	    
	);
    }
}

Remember, the resultset is now an array. Zend\Cache will serialize this and save into file. if we want to call in another resource, we need to call as array, not as Iterator.
for example :

namespace SampleModule\Controller;

use Zend\Mvc\Controller\AbstractActionController;
 
class TablesampleController extends AbstractActionController
{
    protected $sampletable;
    
    public function indexAction()
    {
        $resultSet = $this->getSampleTable()->fetchAll();
        
        //JUST TESTING......
        foreach($resultSet as $row)
        {
            echo $row['name']."<br />";
        }
    }
    
    public function getSampleTable()
    {
        if (!$this->sampletable){
            $this->sampletable = $this->getServiceLocator()->get('SampleModule\Model\SampleTable');
        }
        return $this->sampletable;
    }
}

How about updating data? we have to reset the cache if we want to show updated result.

$this->cache->removeItem('samplecache');

Done !

References :
1. http://www.framework.zend.com/manual/2.0/en/modules/zend.stdlib.hydrator.html