Doctrine 鉴别器如何从地图中知道要使用哪个实体

Question

今天接到一个写判别器的任务，第一次了解Doctrine判别器的工作原理。阅读文档后，这就是我所做的。

我需要创建一个命令来更改 blog/post 作者，然后还要更新有关事件的操作实体。

动作实体：

/**
 * @ORM\Table(name="action")
 * @ORM\Entity()
 * @ORM\InheritanceType("JOINED")
 * @ORM\DiscriminatorColumn(name="discriminator", type="string")
 * @ORM\DiscriminatorMap({"action" = "Action", "blog" = "Blog", "post" = "Post"})
 */
class Action
{ ...

事件中某处命令：

...
$action = new Action();
$action->setType('author_change');

$this->em->persist($action);

这一切都在运行命令之后起作用。唯一的问题是 Action discriminator 每次都保存 'action'，而不是 'blog' 或 'post'。

即使我这样强制列也不会改变:

$action->setDiscriminator('blog');

所以我想我的问题是 Action 是如何知道的以及我应该如何触发从地图中使用哪个鉴别器？

Answer 1

要检查的事项：

您的父实体是 Action，确保 Blog 和 Post 都扩展它
如果您希望您的子class能够访问您的 Action class 中的所有属性（包括 ID）

我用以下 class 尝试了您的设置：

操作：

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\ActionRepository")
 * @ORM\InheritanceType("JOINED")
 * @ORM\DiscriminatorColumn(name="discriminator", type="string")
 * @ORM\DiscriminatorMap({"action" = "Action", "blog" = "Blog", "post" = "Post"})
 */
class Action
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    protected $id;

    /**
     * @ORM\Column(type="string", length=255, nullable=true)
     */
    protected $name;

    // ... getters and setters for $id and $name (notice they are also protected, not private !!!)
}

博客：

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\BlogRepository")
 */
class Blog extends Action
{
    /**
     * @var string
     * @ORM\Column(name="blog_prop", length=255, nullable=true)
     */
    private $blogProp;

    // ... getters and setters for $blogProp
}

Post:

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\PostRepository")
 */
class Post extends Action
{
    /**
     * @var string
     * @ORM\Column(name="post_prop", length=255, nullable=true)
     */
    private $postProp;

    // .... getters and setters for $postProp
}

Doctrine 将为您的每个实体创建一个单独的 table。存储子实体时，还会在父实体中添加一行，并填充公共（继承）字段。子实体特有的属性将插入到它们各自的 table 中。这导致以下数据库结构：

mysql> describe action;
+---------------+--------------+------+-----+---------+----------------+
| Field         | Type         | Null | Key | Default | Extra          |
+---------------+--------------+------+-----+---------+----------------+
| id            | int(11)      | NO   | PRI | NULL    | auto_increment |
| name          | varchar(255) | YES  |     | NULL    |                |
| discriminator | varchar(255) | NO   |     | NULL    |                |
+---------------+--------------+------+-----+---------+----------------+


mysql> describe blog;
+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| id        | int(11)      | NO   | PRI | NULL    |       |
| blog_prop | varchar(255) | YES  |     | NULL    |       |
+-----------+--------------+------+-----+---------+-------+


mysql> describe post;
+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| id        | int(11)      | NO   | PRI | NULL    |       |
| post_prop | varchar(255) | YES  |     | NULL    |       |
+-----------+--------------+------+-----+---------+-------+

控制器：

/**
 * @Route("/test", name="test")
 */
public function test()
{
    $manager = $this->getDoctrine()->getManager();

    $action = new Action();
    $action->setName('my action');

    $blog = new Blog();
    $blog
        ->setName('my blog')
        ->setBlogProp('my blog prop');

    $post = new Post();
    $post
        ->setName('my post')
        ->setPostProp('my post prop');



    $manager->persist($action);
    $manager->persist($blog);
    $manager->persist($post);

    $manager->flush();

}

在运行之后控制器代码：

mysql> select * from action;
+----+-----------+---------------+
| id | name      | discriminator |
+----+-----------+---------------+
|  1 | my post   | post          |
|  2 | my blog   | blog          |
|  3 | my action | action        |
+----+-----------+---------------+
3 rows in set (0.00 sec)

mysql> select * from blog;
+----+--------------+
| id | blog_prop    |
+----+--------------+
|  2 | my blog prop |
+----+--------------+
1 row in set (0.00 sec)

mysql> select * from post;
+----+--------------+
| id | post_prop    |
+----+--------------+
|  1 | my post prop |
+----+--------------+
1 row in set (0.00 sec)

Doctrine 鉴别器如何从地图中知道要使用哪个实体

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