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问题:

I'm currently working with Symfony2 and Doctrine2, but I must override the Doctrine2 EntityManager and add it some "undelete" features (ACLs inside).

So I'm wondering : is there a way to override the EntityManager class and specify Doctrine2 in Symfony2 to use it as implementation of the EntityManager?

Thank you for any help!

回答1:

Yes, it's possible with two steps:

1 - Override the doctrine.orm.entity_manager.class parameter to point to your custom entity manager (which should extend Doctrine\ORM\EntityManager.)

2 - Your custom entity manager must override the create method so that it returns an instance of your class. See my example below, and note the last line regarding MyEntityManager:

public static function create($conn, Configuration $config, EventManager $eventManager = null) {
        if (!$config->getMetadataDriverImpl()) {
            throw ORMException::missingMappingDriverImpl();
        }

        if (is_array($conn)) {
            $conn = \Doctrine\DBAL\DriverManager::getConnection($conn, $config, ($eventManager ? : new EventManager()));
        } else if ($conn instanceof Connection) {
            if ($eventManager !== null && $conn->getEventManager() !== $eventManager) {
                throw ORMException::mismatchedEventManager();
            }
        } else {
            throw new \InvalidArgumentException("Invalid argument: " . $conn);
        }

        // This is where you return an instance of your custom class!
        return new MyEntityManager($conn, $config, $conn->getEventManager());
    }

You'll also need to use the following in your class:

use Doctrine\ORM\EntityManager;
use Doctrine\ORM\Configuration;
use Doctrine\ORM\ORMException;
use Doctrine\Common\EventManager;
use Doctrine\DBAL\Connection;

To be honest, I'm surprised that the 2nd step is required at all, I would think this should be possible to accomplish using only the service container.

回答2:

After Doctrine 2.4 (Doctrine 2.4 release) you need to use decorator for this. Do not extend EntityManager directly. First you need to implement you own entity manager decorator that extends Doctrine\ORM\Decorator\EntityManagerDecorator (like @Dana) But you can't just change doctrine.orm.entity_manager.class to your new decorator because EntityManagerDecorator requires EntityManagerInterface in it's constructor:

public function __construct(EntityManagerInterface $wrapped)

You can't just pass doctrine.orm.entity_manager as a parameter here because it will be a recursion. And don't do like this:

return new self(\Doctrine\ORM\EntityManager::create(

What you need is to configure your decorator in services like a decorator:

yourcompany_entity_manager:
    public: false
    class: YourCompany\ORM\EntityManagerDecorator
    decorates: doctrine.orm.default_entity_manager
    arguments: ["@yourcompany_entity_manager.inner"]

Now you'll have your decorator as a default entity manager for Doctrine. @yourcompany_entity_manager.inner is actually a link to doctrine.orm.default_entity_manager that will be passed to yourcompany_entity_manager constructor.

Symfony docs for configuring decorators: link

Btw this command is very useful to debug your services:

app/console container:debug | grep entity_manager

回答3:

At least in Doctrine/ORM 2.4, the doc string of the EntityManager class explicitly discourages inheriting from Doctrine\ORM\EntityManager, instead they suggest inheriting from Doctrine\ORM\Decorator\EntityManagerDecorator:

/**
 * The EntityManager is the central access point to ORM functionality.
 * ...
 * You should never attempt to inherit from the EntityManager: Inheritance
 * is not a valid extension point for the EntityManager. Instead you
 * should take a look at the {@see \Doctrine\ORM\Decorator\EntityManagerDecorator}
 * and wrap your entity manager in a decorator.
 * ...
 */
/* final */class EntityManager implements EntityManagerInterface
{
    ...

So, extend EntityManagerDecorator and make whatever changes you need. You will need to implement the create() factory method, but you don't need to copy EntityManager's implementation now:

use Doctrine\ORM\Decorator\EntityManagerDecorator;
use Doctrine\Common\EventManager;
use Doctrine\ORM\Configuration;

class MyEntityManager extends EntityManagerDecorator
{
    /**
     * {@inheritDoc}
     */
    public function persist($entity)
    {
        // do something interesting
        parent::persist($entity);
    }

    public function create($conn, Configuration $config, EventManager $eventManager = null)
    {
        return new self(\Doctrine\ORM\EntityManager::create($conn, $config, $eventManager));
    }
}

Then override the doctrine.orm.entity_manager.class parameter to point to your custom entity manager class.

The docs don't cover everything, in many cases you just have to read the code.

回答4:

I found the process of extending the entity manager extremely counterintuitive, despite a decent grasp of concepts including dependency injection, service locator, code generation, caching and the decorator pattern.

Hopefully this concise example will paint a clear picture for you (this expands on the answer by @user2563451)

Symfony Version (Mon Aug 20 13:05:58 CEST 2018)

$ composer info | grep -E -e symfony/framework  -e 'doctrine/(common|orm|dbal)'
doctrine/common             v2.9.0             Common Library for Doctrine projects
doctrine/dbal               v2.8.0             Database Abstraction Layer
doctrine/orm                v2.6.2             Object-Relational-Mapper for PHP
symfony/framework-bundle    v4.1.3             Symfony FrameworkBundle

config/services.yaml

App\Doctrine\ORM\CustomEntityManager:
    public: false # optional afaik
    decorates: doctrine.orm.original_entity_manager
    arguments: [ '@App\Doctrine\ORM\CustomEntityManager.inner' ]

config/packages/doctrine.yaml

doctrine:
    orm:
        auto_generate_proxy_classes: '%kernel.debug%'
        default_entity_manager: original
        entity_managers:
            original:
                connection: from_env
                naming_strategy: doctrine.orm.naming_strategy.underscore
                auto_mapping: false
                mappings:
                    TimeTracking:
                        is_bundle: false
                        type: annotation
                        dir: '%kernel.project_dir%/src/php/Model'
                        prefix: TimeTracking\Model
                        alias: TimeTracking
                        mapping: true
            #mapper_number_5:
            #    (...)

src/php/App/Doctrine/ORM/CustomEntityManager.php

<?php

namespace App\Doctrine\ORM;

use App\Doctrine\ORM\Proxy\SoggyProxyFactory;
use Doctrine\ORM\Decorator\EntityManagerDecorator;
use Doctrine\ORM\Proxy\ProxyFactory;

/**
 * Writes custom proxy-class methods with support for the set-or-get-trait
 * @property  ProxyFactory soggyProxyFactory
 */
class CustomEntityManager extends EntityManagerDecorator
{
    /// SUPER: __construct(EntityManagerInterface $wrapped) { $this->wrapped = $wrapped; }
    private $soggyProxyFactory;
    public function getProxyFactory() {
        $config = $this->getConfiguration();
        if (null === $this->soggyProxyFactory) {
            $this->soggyProxyFactory = new SoggyProxyFactory(
                $this,
                $config->getProxyDir(),
                $config->getProxyNamespace(),
                $config->getAutoGenerateProxyClasses()
            );
        }
        return $this->soggyProxyFactory;
    }
}