php 无法自动装配服务：参数引用类，但不存在此类服务

Cannot autowire service: Argument references class but no such service exists

提问by Donal.Lynch.Msc

I'm upgrading a project from Symfony 3to Symfony 4(https://github.com/symfony/symfony/blob/master/UPGRADE-4.0.md) and I have many repository/services like this:

我正在将一个项目从Symfony 3升级到Symfony 4( https://github.com/symfony/symfony/blob/master/UPGRADE-4.0.md)，我有很多这样的存储库/服务：

namespace App\Entity;

use App\Entity\Activation;
use Doctrine\ORM\EntityRepository;
use Predis\Client;

class ActivationRepository extends EntityRepository
{
    // ...
}

And when I try to run the project in the browser like this:

当我尝试像这样在浏览器中运行项目时：

http://localhost:8000/login

I get this error:

我收到此错误：

(1/1) RuntimeException
Cannot autowire service "App\Entity\ActivationRepository": 
argument "$class" of method 
"Doctrine\ORM\EntityRepository::__construct()" 
references class "Doctrine\ORM\Mapping\ClassMetadata" 
but no such service exists.

Does this mean you have to create a service for "Doctrine\ORM\Mapping\ClassMetadata"in your services.yaml file?

这是否意味着您必须在 services.yaml 文件中为“Doctrine\ORM\Mapping\ClassMetadata”创建一个服务？

Thanks to autowiring my new services.yaml file is fairly small compared to the old one, which had 2000+ lines. The new services.yaml just has several of these (so far):

由于自动装配，我的新 services.yaml 文件与旧文件相比相当小，旧文件有 2000 多行。新的 services.yaml 只有其中几个（到目前为止）：

App\:
    resource: '../src/*'

# Controllers
App\Controller\:
    resource: '../src/Controller'
    autowire: true
    public: true
    tags: ['controller.service_arguments']

# Models
App\Model\:
    resource: '../src/Model/'
    autowire: true
    public: true

// etc

Question: Do you really need to add service definitions to services.yaml for third party vendor classes? And if so, can I get an example of how to do that please? Any advice from anyone who has already upgraded from Symfony 3to Symfony 4would be great.

问题：您真的需要为第三方供应商类的 services.yaml 添加服务定义吗？如果是这样，我能得到一个如何做到这一点的例子吗？任何已经从Symfony 3升级到Symfony 4 的人的任何建议都会很棒。

PHP 7.2.0-2+ubuntu16.04.1+deb.sury.org+2 (cli) (built: Dec 7 2017 20:14:31) ( NTS ) Linux Mint 18, Apache2 Ubuntu.

PHP 7.2.0-2+ubuntu16.04.1+deb.sury.org+2 (cli) (build: Dec 7 2017 20:14:31) ( NTS ) Linux Mint 18, Apache2 Ubuntu。

EDIT / FYI:

编辑/仅供参考：

This is the "Doctrine\ORM\EntityRepository::__construct()" which the ActivationRepository extends:

这是 ActivationRepository 扩展的“Doctrine\ORM\EntityRepository::__construct()”：

/**
     * Initializes a new <tt>EntityRepository</tt>.
     *
     * @param EntityManager         $em    The EntityManager to use.
     * @param Mapping\ClassMetadata $class The class descriptor.
     */
    public function __construct(EntityManagerInterface $em, Mapping\ClassMetadata $class)
    {
        $this->_entityName = $class->name;
        $this->_em         = $em;
        $this->_class      = $class;
    }

which is located here:

位于此处：

/vendor/doctrine/orm/lib/Doctrine/ORM/EntityRepository.php

回答by Federkun

Starting from the 1.8 version of DoctrineBundle, you can extends your class using Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepositoryinstead of Doctrine\ORM\EntityRepository. The result will be the same, but this support the autowire.

从 1.8 版本的 DoctrineBundle 开始，您可以使用Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository代替来扩展您的类 Doctrine\ORM\EntityRepository。结果将是相同的，但这支持自动装配。

Example:

例子：

use App\Entity\Activation;
use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
use Doctrine\Common\Persistence\ManagerRegistry;

class ActivationRepository extends ServiceEntityRepository
{
    public function __construct(ManagerRegistry $registry)
    {
        parent::__construct($registry, Activation::class);
    }

    // ...
}

回答by Federkun

Do you really need to add service definitions to services.yaml for third party vendor classes?

您真的需要为第三方供应商类的 services.yaml 添加服务定义吗？

No, don't do that. My personal suggestion is: don't extend EntityRepository. Ever. You don't want your repository's interface to have method like createQueryor flush. At least, you don't want that if you consider a repository just like a collection of objects. If you extend EntityRepositoryyou will have a leaky abstraction.

不，不要那样做。我个人的建议是：不要扩展EntityRepository. 曾经。您不希望存储库的接口具有像createQuery或 之类的方法flush。至少，如果您将存储库视为对象的集合，那么您不希望这样。如果您扩展，EntityRepository您将有一个泄漏的抽象。

Instead you can inject the EntityManagerinside your repository, and that's it:

相反，您可以注入EntityManager存储库内部，就是这样：

use App\Entity\Activation;
use App\Repository\ActivationRepository;
use Doctrine\ORM\EntityManagerInterface;

final class DoctrineActivationRepository implements ActivationRepository
{
    private $entityManager;
    private $repository;

    public function __construct(EntityManagerInterface $entityManager)
    {
        $this->entityManager = $entityManager;
        $this->repository = $this->entityManager->getRepository(Activation::class);
    }

    public function store(Activation $activation): void
    {
        $this->entityManager->persist($activation);
        $this->entityManager->flush();
    }

    public function get($id): ?Activation
    {
        return $this->repository->find($id);
    }

    // other methods, that you defined in your repository's interface.
}

No other steps are required.

不需要其他步骤。