<?php

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity()
 */
class Comment
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    private id;

    /**
     * @ORM\Column(type="text")
     */
    privatecontent;

    /**
     * @ORM\ManyToOne(targetEntity="Commentable", inversedBy="comments")
     */
    private $commentable;

    // ...
}

<?php

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity()
 * @ORM\InheritanceType("JOINED")
 * @ORM\DiscriminatorColumn(name="type", type="string")
 * @ORM\DiscriminatorMap({"article" = "Article", "user" = "User"})
 */
abstract class Commentable
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    protected id;

    /**
     * @ORM\OneToMany(targetEntity="Comment", mappedBy="commentable")
     */
    protectedcomments;

    // ...
}

<?php

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity()
 */
class Article extends Commentable
{
    /**
     * @ORM\Column(type="text")
     */
    private content;

    // ...
}

/**
 * @ORM\Entity()
 */
class User extends Commentable
{
    /**
     * @ORM\Column(type="string", length=255)
     */
    privatename;

    // ...
}

<?php

// ... 实体和其他相关命名空间的使用

entityManager = // 获取实体管理器的代码

// 创建一个新的用户user = new User();
user->setName('John Doe');entityManager->persist(user);entityManager->flush();

// 创建一篇新文章并发布
article = new Article();article->setContent('New article');
entityManager->persist(article);
entityManager->flush();

// 用户发表一条评论userComment = new Comment();
userComment->setContent('User comment');userComment->setCommentable(user);entityManager->persist(userComment);entityManager->flush();

// 文章发表一条评论
articleComment = new Comment();articleComment->setContent('Article comment');
articleComment->setCommentable(article);
entityManager->persist(articleComment);
entityManager->flush();

// 检索并输出所有评论comments = entityManager->getRepository(Comment::class)->findAll();
foreach (comments as comment) {
    echocomment->getContent() . ' for ' . get_class(comment->getCommentable()) . ' ' .comment->getCommentable()->getId() . "\n";
}

User comment for User 1
Article comment for Article 1