Symfony2 flash消息作为事件监听器来处理错误

我们已经设置了一个事件监听器，当实体被更新、删除或持久化时触发flash消息，但是我们不能完全管理的是如何处理错误。

以下是services.yml

flash_messages:
    class: Acme'AcmeBundle'EventListener'FlashMessages
    tags:
        - { name: doctrine.event_listener, event: postUpdate }
        - { name: doctrine.event_listener, event: postRemove }
        - { name: doctrine.event_listener, event: postPersist }
    arguments: [ @session, @translator ]

这是Acme/AcmeBundle/EventListener/FlashMessages.php

namespace Acme'AcmeBundle'EventListener;
use
    Doctrine'ORM'Event'LifecycleEventArgs,
    Symfony'Component'HttpFoundation'Session'Session,
    Symfony'Component'Translation'TranslatorInterface
;
class FlashMessages
{
    private $session;
    protected $translator;
    public function __construct(Session $session, TranslatorInterface $translator)
    {
        $this->session = $session;
        $this->translator = $translator;
    }
    public function postUpdate(LifecycleEventArgs $args)
    {
        $entity = $args->getEntity();
        $this->session->getFlashBag()->add(
            'success',
            $this->translator->trans(
                '%name% entity.write.success',
                array('%name%' => $entity->getClassName())
            )
        );
    }
    public function postRemove(LifecycleEventArgs $args)
    {
        $entity = $args->getEntity();
        $this->session->getFlashBag()->add(
            'success',
            $this->translator->trans(
                '%name% entity.delete.success',
                array('%name%' => $entity->getClassName())
            )
        );
    }
    public function postPersist(LifecycleEventArgs $args)
    {
        $entity = $args->getEntity();
        $this->session->getFlashBag()->add(
            'success',
            $this->translator->trans(
                '%name% entity.create.success',
                array('%name%' => $entity->getClassName())
            )
        );
    }
}

我们要做的是清理控制器并将所有错误消息移动到事件侦听器中。例如，这是我们的DeliveryController.php:

/**
 * Finds and displays a Delivery entity.
 *
 * @Route("/{id}", name="delivery_show")
 * @Method("GET")
 * @Template()
 */
public function showAction($id)
{
    $em = $this->getDoctrine()->getManager();
    $entity = $em->getRepository('AcmeBundle:Delivery')->find($id);
    if (!$entity) {
        /**
         * @todo move this code to eventListener
         */
        $entity = new Delivery();
        $this->get('session')->getFlashBag()->add(
            'danger',
            $this->get('translator')->trans(
                '%name% entity.find.fail',
                array('%name%' => $entity->getClassName())
            )
        );
        // end @todo
        return new RedirectResponse($this->generateUrl('delivery'));
    }
    return array(
        'entity'      => $entity,
        'menu_tree' => $this->menu_tree,
    );
}

与此类似，理想情况下，我们也希望在实体创建、持久化和删除失败时处理错误。

作为参考，翻译由Acme/AcmeBundle/Resources/translations/messages.en.yml

%name% entity.create.fail: There wes an error creating the %name%. Please try again later.
%name% entity.create.success: %name% created successfully.
%name% entity.write.fail: There wes an error saving the %name%. Please try again later.
%name% entity.write.success: %name% saved successfully.
%name% entity.delete.fail: There wes an error deleting the %name%. Please try again later.
%name% entity.delete.success: %name% deleted successfully.
%name% entity.find.fail: %name% not found.

$entity->getClassName()位于每个实体中，如下所示:

private $className;
/**
 * Get class name
 * @return string
 */
public function getClassName()
{
    $entity = explode('''', get_class($this));
    return end($entity);
}