将EntityManager依赖服务注入侦听器 [英] Injecting EntityManager-dependend service into Listener

问题描述

我试图将我的一项服务注入到EntityListener中，以便在实体更新时调用某些特定于应用程序的行为.

I am trying to inject one of my services into an EntityListener in order to call some application specific behaviour when an entity gets updated.

我的Logger服务，用于将事件存储在数据库的LogEntry实体中:

My Logger service, used to store events in a LogEntry entity in my database:

class Logger
{
    /**
     * @var EntityManager $manager The doctrine2 manager
     */
   protected $manager;
   //...
}

听众:

class EntityListener
{
    public function __construct(Logger $logger)
    {
        $this->logger = $logger;
         // ...
    }
}

以及我的service.yml中的服务定义:

And the service definitions in my service.yml:

listener:
    class: Namespace\EntityListener
    arguments: [@logger]
    tags:
        - { name: doctrine.event_listener, event: preUpdate }

logger:
    class: Namespace\Logger
    arguments: [@doctrine.orm.entity_manager]

不幸的是，它导致ServiceCircularReferenceException:

检测到服务"doctrine.orm.default_entity_manager"的循环引用，路径:"doctrine.orm.default_entity_manager-> doctrine.dbal.default_connection->侦听器->记录器".

Circular reference detected for service "doctrine.orm.default_entity_manager", path: "doctrine.orm.default_entity_manager -> doctrine.dbal.default_connection -> listener -> logger".

问题显然是我将doctrine注入了我的服务，同时它也被自动注入了我的监听器.我该如何进行?我发现非常相似的问题但是可以接受的答案是注入容器，这显然是不利的.

The problem obviously is that I inject the doctrine into the my service while it is also automatically injected into my listener. How do I proceed? I found a very similar question but the accepted answer is to inject the container which is obviously not favourable.

任何有关如何解决我的问题的建议将不胜感激.

Any suggestions on how to solve my issue would be appreciated.

小注释:我想避免依赖惰性服务的解决方案(如果可能).

Small side note: I would like to avoid a solution depending on lazy services if possible.

推荐答案

首先，我从EventListener切换为EventSubscriber.从文档:

First of all I switched from an EventListener to an EventSubscriber. From the docs:

Doctrine定义了可以侦听Doctrine事件的两种对象:侦听器和订阅者.两者非常相似，但是听众却更加直接.

Doctrine defines two types of objects that can listen to Doctrine events: listeners and subscribers. Both are very similar, but listeners are a bit more straightforward.

事实证明，可以像这样通过传递的$args参数访问ObjectManager:

It turns out one can access the ObjectManager via the passed $args-parameter like so:

/** @var Doctrine\Common\Persistence\ObjectManager $manager */
$manager = $args->getObjectManager();

因此可以直接在回调中使用它:

So either use it directly in the callback:

public function postUpdate(LifecycleEventArgs $args)
{
    $manager = $args->getObjectManager();
    // ...

...或将其设置为对象字段:

...or set it to an object field:

/** @var ObjectManager $manager */
private $manager;

public function postUpdate(LifecycleEventArgs $args)
{
    $this->manager = $args->getObjectManager();
    // ...

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