使用事件监听器创建preUpdate或preFlush事件

Question

我有一个onFlush()事件，它工作正常，但我需要将其转换为preFlush()或preUpdate()，两者都可以接受。我尝试使用preFlush()，但由于某种原因它不起作用。甚至没有错误信息。我漏掉了什么？

测试结果：我在preFlush()中放置了exit以查看是否被调用。结果是：1，所以foreach()从未运行！它是一个空数组。我还测试了preUpdate()，其中所有行都会运行，但没有插入数据。

public function preFlush(PreFlushEventArgs $args)
{
    $em = $args->getEntityManager();
    $uow = $em->getUnitOfWork();
    echo '1';
    foreach ($uow->getScheduledEntityUpdates() as $entity) {
        echo '2';
        if ($entity instanceof User) {
            echo '3';
        }
    }
    exit;
}

阅读文档后，我创建了它们。

service.yml

services:
    entity.event_listener.user:
        class:  Site\FrontBundle\EventListener\Entity\UserListener
        tags:
            - { name: doctrine.event_listener, event: preUpdate }
            - { name: doctrine.event_listener, event: onFlush }
            - { name: doctrine.event_listener, event: preFlush }

onFlush()示例：

class UserListener
{
    public function onFlush(OnFlushEventArgs $args)
    {
        $em = $args->getEntityManager();
        $uow = $em->getUnitOfWork();

        foreach ($uow->getScheduledEntityUpdates() as $entity) {
            if ($entity instanceof User) {
                $userLog = new UserLog();
                $userLog->setDescription($entity->getId() . ' being updated.');

                $em->persist($userLog);

                // Instead of $em->flush() cos we're already in flush process
                $userLogMetadata = $em->getClassMetadata(get_class($userLog));
                $uow->computeChangeSet($userLogMetadata, $userLog);
            }
        }
    }
}

preFlush()示例不起作用：

class UserListener
{
    public function preFlush(PreFlushEventArgs $args)
    {
        $em = $args->getEntityManager();
        $uow = $em->getUnitOfWork();

        foreach ($uow->getScheduledEntityUpdates() as $entity) {
            if ($entity instanceof User) {
                $userLog = new UserLog();
                $userLog->setDescription($entity->getId() . ' being updated.');

                $em->persist($userLog);

                // Instead of $em->flush() cos we're already in flush process
                $userLogMetadata = $em->getClassMetadata(get_class($userLog));
                $uow->computeChangeSet($userLogMetadata, $userLog);
            }
        }
    }
}

preUpdate()示例不起作用

class UserListener
{
    public function preUpdate(LifecycleEventArgs $args)
    {
        $entity = $args->getEntity();
        $em = $args->getEntityManager();
        $uow = $em->getUnitOfWork();

        if ($entity instanceof User) {
            $userLog = new UserLog();
            $userLog->setDescription($entity->getId() . ') been updated.');

            $em = $args->getEntityManager();
            $em->persist($userLog);
            $userLogMetadata = $em->getClassMetadata(get_class($userLog));
            $uow->computeChangeSet($userLogMetadata, $userLog);
        }
    }
}

- BentCoder

---

你能添加服务配置部分吗？ - devsheeep

在 preFlush 中，您应该使用 $args->getEntity() 而不是 $uow->getScheduledEntityUpdates()。 - Aljana Polanc

@aljana - PreFlushEventArgs类没有提供getEntity()方法供我们使用。 - BentCoder

你说得对，抱歉。我建议你编写自己的事件来创建日志，因为当涉及插入新实体时，Doctrine 的事件会变得棘手。 - Aljana Polanc

@aljana - 没问题。我找到了一个例子，我会修改它并在这里发布，让其他人可以看到应该如何处理。 - BentCoder

Answer 1

解决方案：

诀窍在于在postFlush()事件中，在preUpdate()之后持久化。

注意：虽然这可能不是最佳解决方案，但它回答了问题，然而它可以通过Event Subscriber或简单的onFlush() -> $uow->getScheduledEntityUpdates()在Event Listener中完成。

Service.yml

services:

    entity.event_listener.user_update:
        class:  Site\FrontBundle\EventListener\Entity\UserUpdateListener
        tags:
            - { name: doctrine.event_listener, event: preUpdate }
            - { name: doctrine.event_listener, event: postFlush }

事件监听器

<?php

namespace Site\FrontBundle\EventListener\Entity;

use Doctrine\ORM\Event\LifecycleEventArgs;
use Doctrine\ORM\Event\PostFlushEventArgs;
use Site\FrontBundle\Entity\User;
use Site\FrontBundle\Entity\UserLog;

class UserUpdateListener
{
    private $log = array();

    public function preUpdate(LifecycleEventArgs $args)
    {
        $entity = $args->getEntity();

        // False check is compulsory otherwise duplication occurs
        if (($entity instanceof User) === false) {
            $userLog = new UserLog();
            $userLog->setDescription($entity->getId() . ' being updated.');

            $this->log[] = $userLog;
        }
    }

    public function postFlush(PostFlushEventArgs $args)
    {
        if (! empty($this->log)) {
            $em = $args->getEntityManager();
            foreach ($this->log as $log) {
                $em->persist($log);
            }
            $em->flush();
        }
    }
} 

- BentCoder

---

不要这样做。在postFlush事件中调用EntityManager#flush()是不安全的。详见Doctrine文档。 - Jules Lamur

Answer 2

阅读文档，

http://doctrine-orm.readthedocs.org/en/latest/reference/events.html#onflush

它没有提到preFlush具有关于更改的信息（我指的是entityManager）。

如果您查看Doctrine\ORM\UnitOfWork，则会发现更改集在preFlush事件之后计算，因此，如果要与更改的实体进行交互，应使用onFlush。

// Raise preFlush
    if ($this->evm->hasListeners(Events::preFlush)) {
        $this->evm->dispatchEvent(Events::preFlush, new PreFlushEventArgs($this->em));
    }

// Compute changes done since last commit.
if ($entity === null) {
    $this->computeChangeSets();
} elseif (is_object($entity)) {
    $this->computeSingleEntityChangeSet($entity);
} elseif (is_array($entity)) {
    foreach ($entity as $object) {
        $this->computeSingleEntityChangeSet($object);
    }
}

- Bartłomiej Wach

---

如何在onFlush()监听函数中，如果某些条件失败，中止刷新操作？ - jitendra

Answer 3

Dear BentCoder: 我正在使用Symfony 2.7版本。当我在事件监听器中使用$em->flush时，像你的帖子一样，会出现这个错误： 点击这里查看错误描述 这是我的解决方案：

Service.yml

services:
    app.listener:
        class: AppBundle\EventListener\DoctrineListener
        arguments: ["@service_container"]
        tags:
            - { name: doctrine.event_listener, event: preUpdate, method: preUpdate }
            - { name: doctrine.event_listener, event: postUpdate, method: postUpdate }

事件监听器

namespace AppBundle\EventListener;

use Symfony\Component\DependencyInjection\ContainerInterface;
use Doctrine\ORM\Event\LifecycleEventArgs;

use AppBundle\Entity;

/**
 * Log activity on website
 * Class DoctrineListener
 * @package AppBundle\EventListener
 */
class DoctrineListener
{
    /**
     * @var ContainerInterface
     */
    private $_container;

    /**
     * @var Array
     */
    private $_activities;

    /**
     * DoctrineListener constructor.
     * @param ContainerInterface $container
     */
    public function __construct(ContainerInterface $container)
    {
        $this->_container = $container;
    }

    /**
     * @param LifecycleEventArgs $args
     */
    public function preUpdate(LifecycleEventArgs $args)
    {
        $entityManager = $args->getEntityManager();
        $entity = $args->getEntity();
        $activityEntity = new Entity\Activity();
        $activityEntity->setAction(Entity\Activity::ACTION_EDIT);
        $activityEntity->setActionAt(new \DateTime());
        $activityEntity->setIpAddress($this->_container->get('request')->getClientIp());
        switch (true) {
            case $entity instanceof Entity\Goods:
                $repository = $entityManager->getRepository('AppBundle:Goods');
                $activityEntity->setType(Entity\Activity::TYPE_GOODS);
                $message = 'User: <strong>%s</strong> sửa mẫu hàng hóa <strong>%s</strong>';
                break;
            default:
                return;
        }
        if (isset($repository) && $args->getEntityChangeSet()) {
            $user = $this->_container->get('security.context')->getToken()->getUser();
            $recordBefore = clone $entity;
            foreach ($args->getEntityChangeSet() as $key => $value) {
                $method = 'set'.ucfirst($key);
                $recordBefore->$method($value[0]);
            }
            $activityEntity->setFosUser($user);
            $activityEntity->setRecordBefore(serialize($recordBefore));
            $activityEntity->setRecordAfter(serialize($entity));
            $activityEntity->setMessage(
                sprintf(
                    $message,
                    $user->getUserProfile()->getFullName(),
                    (string) $recordBefore
                )
            );
            $this->_activities[] = $activityEntity;
        }
        return;
    }

    /**
     * @param LifecycleEventArgs $args
     */
    public function postUpdate(LifecycleEventArgs $args)
    {
        if (sizeof($this->_activities)) {
            $entityManager = $args->getEntityManager();
            foreach ($this->_activities as $activity) {
                $entityManager->persist($activity);
            }
            $entityManager->flush();
        }
    }
}

希望这能帮助到某人！

- De Nguyen