原则ORM：使用接口作为不同实体的关系吗？ [英] Doctrine ORM: use interface as relation for different entities?

问题描述

如何在学说中的多对多关系中使用界面？

How to use interface in many-to-many relation in doctrine?

在我的应用中，有3个实体：用户，汽车和驾驶员。用户可以将汽车和驾驶员添加为收藏夹。因此，我做了一个简化的结构：

In my app there is 3 entities: User, Car and Driver. User can add cars and drivers as favorites. So i made this structure (simplified):

具有最喜欢的功能的用户：

User, who has favorite feature:

namespace Acme\AppBundle\Entities;

use Acme\AppBundle\Interfaces\HasFavorites;

/** @ORM\Entity */
class User implements HasFavorites
{
    /** @ORM\ManyToMany(targetEntity="Acme\AppBundle\Entities\Favorite") */
    protected $favorites;

    public function getFavorites() : ArrayCollection
    {
        return $this->favorites;
    }

    public function addFavorite(Favorite $favorite)
    {
        $this->favorites->add($favorite);
    }
}

收藏夹对象模型：

namespace Acme\AppBundle\Entities;

use Acme\AppBundle\Interfaces\Favoritable;

/** @ORM\Entity */
class Favorite
{
    /** @ORM\ManyToOne(targetEntity="Acme\AppBundle\Entities\User") */
    private $owner;

    /** @ORM\ManyToOne(targetEntity="Acme\AppBundle\Interfaces\Favoritable") */
    private $target;

    public function __construct(User $owner, Favoritable $target)
    {
        $this->owner  = $owner;
        $this->target = $target;
    }

    public function getOwner() : User
    {
        return $this->owner;
    }

    public function getTarget() : Favoritable
    {
        return $this->target;
    }
}

汽车和驾驶员–可以添加到收藏夹的实体：

Car and Driver – entities that can be added to favorites:

namespace Acme\AppBundle\Entities;

use Acme\AppBundle\Interfaces\Favoritable;

/** @ORM\Entity */
class Car implements Favoritable { /* ... */ }

/** @ORM\Entity */
class Driver implements Favoritable { /* ... */ }

但是当我使用命令 ./ bin / console doctrine：schema：update --force 更新架构时，我会报错

But when i update my schema with command ./bin/console doctrine:schema:update --force, i'll get error

[Doctrine\Common\Persistence\Mapping\MappingException]
Class 'Acme\AppBundle\Interfaces\Favoritable' does not exist

我测试中的这段代码也可以正常工作（如果我不使用数据库），所以命名空间和文件路径是正确的：

This code in my tests also working ok (if i don't work with database) so namespaces and file paths are correct:

$user = $this->getMockUser();
$car  = $this->getMockCar();
$fav  = new Favorite($user, $car);
$user->addFavorite($fav);
static::assertCount(1, $user->getFavorites());
static::assertEquals($user, $fav->getUser());

如何建立这种关系？我在搜索中发现的东西只有在逻辑上汽车/驾驶员基本相同的情况下才出现。

How to do this relation? What i've found yet in search that is only situation when Car/Driver are mostly the same by logic.

我在数据库中需要的只是这样的（期望），但并不是那么重要：

What i need in database is just something like this (desired) but it's not so important:

+ ––––––––––––– +   + ––––––––––––– +   + –––––––––––––––––––––––––––––––––– +
|     users     |   |      cars     |   |            favorites               |
+ –– + –––––––– +   + –– + –––––––– +   + –––––––– + ––––––––– + ––––––––––– +
| id |   name   |   | id |   name   |   | owner_id | target_id | target_type |
+ –– + –––––––– +   + –– + –––––––– +   + –––––––– + ––––––––– + ––––––––––– +
| 42 | John Doe |   | 17 | BMW      |   |       42 |        17 | car         |
+ –– + –––––––– +   + –– + –––––––– +   + –––––––– + ––––––––– + ––––––––––– +

推荐答案

使用Doctrine的 ResolveTargetEntityListener ，您可以按照您的方式注释关系以目标 interface 为目标，然后将其解析为特定的实体。

With Doctrine's ResolveTargetEntityListener you can annotate a relationship to target interface the way you did, and then resolve it to a specific entity.

更多有关Doctrine文档的信息： http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/cookbook/resolve-target-entity-listener.html

More in Doctrine docs: http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/cookbook/resolve-target-entity-listener.html

或者在这里，如果您使用的是Symfony框架： http://symfony.com/doc/current/doctrine/resolve_target_entity.html

Or here, if you're using Symfony framework: http://symfony.com/doc/current/doctrine/resolve_target_entity.html

但是，您无法实现自己的目标想要这样-一个接口被分解为多个实现该i的实体接口使用区分符。这不是AFAIK。您只能将一个接口解析为一个实体，以便在一个表中使用。

HOWEVER, you can't achieve what you want with this - one interface being resolved into multiple entities implementing this interface using a "discriminator". That's not possible AFAIK. You can only resolve one interface to one entity for use within one table.

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