Circular reference Doctrine - Twig

Question

I do in the application user registration, and I want to be notified by email when registering. I created for this services:

app.mail_service:
    class: AppBundle\Mail\MailService
    arguments: ["@mailer", "@templating"]

app.listener.user:
    class: AppBundle\EventListener\UserSubscriber
    arguments: ["@app.mail_service"]
    tags:
        - { name: doctrine.event_subscriber, connection: default }

templating - TwigEngine

MailService class:

class MailService
{
private $mailer;

private $renderer;

public function __construct(Swift_Mailer $mailer, EngineInterface $renderer)
{
    $this->mailer = $mailer;
    $this->renderer = $renderer;
}

/**
 * @return Swift_Mailer
 */
public function getMailer()
{
    return $this->mailer;
}

/**
 * @return EngineInterface
 */
public function getRenderer()
{
    return $this->renderer;
}

public function sendRegistrationMail(User $user)
{
    /** @var \Swift_Message $message */
    $message = $this->getMailer()
        ->createMessage();

    $message->setSubject('You successful register in website')
        ->addTo($user->getEmail())
        ->setBody($this->getRenderer()->render('AppBundle:Mail:register.html.twig', array(
            'user' => $user
        )), 'text/html', 'UTF-8');

    return $this->getMailer()->send($message);
}
}

And User subscriber listener:

class UserSubscriber implements EventSubscriber
{
/**
 * @var MailService
 */
private $mailService;

public function __construct(MailService $mailService)
{
    $this->mailService = $mailService;
}

public function postPersist(LifecycleEventArgs $args)
{
    $entity = $args->getEntity();
    if ($entity instanceof User) {
        $this->mailService->sendRegistrationMail($entity);
    }
}

/**
 * Returns an array of events this subscriber wants to listen to.
 *
 * @return array
 */
public function getSubscribedEvents()
{
    return array(
        'postPersist',
    );
}
}

When I try to add a new user, I get the exception:

Circular reference detected for service "security.authorization_checker", path: "sensio_framework_extra.security.listener -> security.authorization_checker -> security.authentication.manager -> security.user.provider.concrete.entity_provider -> doctrine.orm.default_entity_manager -> doctrine.dbal.default_connection -> app.listener.user -> app.mail_service -> templating -> twig -> security.context".

As I understand it, the error occurs due to the fact that the Twig tries to EntityManager for Security checker.

In this article, the author uses a simple scheme, but there is also used in the Twig in Doctrine EventListener. That is not throwing exceptions.

Answer 1

I would say the cleanest approach to avoid a circular reference would be inject the event dispatcher to your doctrine listener. Then in the doctrine listener dispatch a user registered event that would then have a Symfony kernel listener that can then send the email.

Doctrine Subscriber

class UserSubscriber implements EventSubscriber
{
    /**
     * @var EventDispatcherInterface
     */
    private $dispatcher;

    public function __construct(EventDispatcherInterface $dispatcher)
    {
        $this->dispatcher = $dispatcher;
    }

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

        if ($entity instanceof User) {
            $dispatcher->dispatch('acme.user.registered', new UserEvent($user));
        }
    }

    /**
     * Returns an array of events this subscriber wants to listen to.
     *
     * @return array
     */
    public function getSubscribedEvents()
    {
        return array(
            'postPersist',
        );
    }
}

User Event

class UserEvent extends GenericEvent
{
    public function __construct(User $user, array $arguments = array())
    {
        parent::__construct($user, $arguments);
    }

    /**
     * @return User
     */
    public function getUser()
    {
        return $this->getSubject();
    }
}

Symfony Subscriber

class UserRegistrationMailSubscriber implements EventSubscriberInterface
{
    /**
     * @var MailService
     */
    private $mailService;

    public function __construct(MailService $mailService)
    {
        $this->mailService = $mailService;
    }

    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents()
    {
        return array(
            'acme.user.registered'  => 'sendRegistrationMail',
        );
    }

    /**
     * @param UserEvent $event
     */
    public function sendRegistrationMail(UserEvent $event)
    {
        $this->mailService->sendRegistrationMail($event->getUser());
    }
}

Services

app.mail_service:
    class: AppBundle\Mail\MailService
    arguments: ["@mailer", "@templating"]

app.doctrine.listener.user:
    class: AppBundle\EventListener\UserSubscriber
    arguments: ["@event_dispatcher"]
    tags:
        - { name: doctrine.event_subscriber, connection: default }

app.kernel.listener.user_registartion_mail:
   class: AppBundle\EventListener\UserRegistrationMailSubscriber
   arguments: ["@app.mail_service"}
   tags:
        - { name: kernel.event_subscriber }