Zend Framework 2 : Step by Step Create Custom View Strategy

Zend Framework 2 ships with three Rendering and Response Strategies that we can use within our application : PhpRendererStrategy, JsonStrategy, and FeedStrategy. If we want to use a custom strategy, for example : add content-type : image/png to all header response, we should create custom view strategy to create custom response. I will give you an example how to create it.

1. create a view strategy

namespace YourModule\View\Strategy;

use Zend\EventManager\ListenerAggregateInterface;
use Zend\EventManager\EventManagerInterface;
use Zend\Mvc\MvcEvent;
use Zend\View\Renderer\RendererInterface;
use Zend\View\ViewEvent;
use Zend\View\Model\ViewModel;
 
class ImageStrategy implements ListenerAggregateInterface
{
    protected $renderer;
    protected $listeners = array();
    
    public function __construct(RendererInterface $renderer)
    {
        $this->renderer = $renderer;
    }
    
    public function attach(EventManagerInterface $events, $priority = 1)
    {                               
       $this->listeners[] = $events->attach(ViewEvent::EVENT_RENDERER, array($this, 'selectRenderer'), $priority);
       $this->listeners[] = $events->attach(ViewEvent::EVENT_RESPONSE, array($this, 'injectResponse'), $priority);
    }
    
    public function selectRenderer(ViewEvent $e)
    {
        return $this->renderer;
    }
    
    public function injectResponse(ViewEvent $e)
    {
        $renderer = $e->getRenderer();
        if ($renderer !== $this->renderer) {
            return;
        }

        $result   = $e->getResult();
        
        $response = $e->getResponse();
        $response->setContent($result);
        $headers = $response->getHeaders();
        $headers->addHeaderLine('content-type', 'image/png');
    }
    
    public function detach(EventManagerInterface $events)
    {
        foreach ($this->listeners as $index => $listener) {
            if ($events->detach($listener)) {
                unset($this->listeners[$index]);
            }
        }
    }
}

2. Create Factory

namespace YourModule\View\Strategy;

use Zend\ServiceManager\FactoryInterface;
use Zend\ServiceManager\ServiceLocatorInterface;

class ImageFactory implements FactoryInterface
{
    public function createService(ServiceLocatorInterface $serviceLocator)
    {
        $viewRenderer = $serviceLocator->get('ViewRenderer');
        return new ImageStrategy($viewRenderer);
    }
}

3. Register in service manager

return array(
        'factories' => array(
            'ImageStrategy' => 'YourModule\View\Strategy\ImageFactory',
        )
);	

4. Register in view_manager in your module.config.php

'view_manager' => array(
       'strategies' => array(
           'ImageStrategy'
        ), 
 ),

Done !

What if we need the custom strategy is for specific module ? This is it :

namespace YourModule;

use Zend\Mvc\MvcEvent;

class Module
{
    public function onBootstrap(MvcEvent $e)
    {
	$sharedEvents        = $e->getApplication()->getEventManager()->getSharedManager();
	$sm = $e->getApplication()->getServiceManager(); 
	
	$sharedEvents->attach(__NAMESPACE__, MvcEvent::EVENT_DISPATCH, function($e) use ($sm) {
	    $strategy = $sm->get('ImageStrategy');
	    $view     = $sm->get('ViewManager')->getView();
	    $strategy->attach($view->getEventManager());
        }, 100);
    }
    
    public function getServiceConfig()
    {
	return array(
                    'factories' => array(
                	'ImageStrategy' => 'YourModule\View\Strategy\ImageFactory',
                    )
        );
    }
    
    public function getAutoloaderConfig(){ /*common code */ }
    public function getConfig(){ /*common code */ }
}

Testing, read image file from your controller :

namespace YourModule\Controller;

use Zend\Mvc\Controller\AbstractActionController;

class SkeletonController extends AbstractActionController
{
   public function fooAction()
    {
        return readfile('./public/images/zf2-logo.png');
    }
}

Reference :
1. http://zf2.readthedocs.org/en/latest/modules/zend.view.quick-start.html
2. http://juriansluiman.nl/en/article/119/attach-a-view-strategy-for-specific-modules

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