Php Symfony3条令单表固有SQL状态[23000]：完整性约束冲突

我是新来的Symfony，我正在尝试做一个简单的博客。我的数据库中有用户作为注释的作者和两种类型的注释——PostComment和ReplyComment，它们都扩展了抽象类注释。我正在尝试将注释保存到DB，但遇到以下错误：

执行“插入注释文本”时发生异常， 作者id、帖子id、注释类型值？、？、？、？'以及参数 [Lorem ipsum，1，1，发表评论]：

SQLSTATE[23000]：完整性约束冲突：1452无法添加或 更新子行：外键约束失败 blog_symfony.comment，约束FK_9474526CDB1174D2国外 关键帖子注释id引用注释id

这是抽象注释类：

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity()
 * @ORM\Table(name="comment")
 * @ORM\InheritanceType("SINGLE_TABLE")
 * @ORM\DiscriminatorColumn(name="comment_type", type="string")
 * @ORM\DiscriminatorMap({"post_comment" = "PostComment", "reply_comment" = "ReplyComment"})
 */
abstract class Comment
{

    /**
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     * @ORM\Column(type="integer")
     */
    protected $id;

    /**
     * @ORM\ManyToOne(targetEntity="AppBundle\Entity\User", inversedBy="userComments")
     */
    protected $author;

    /**
     * @ORM\Column(type="string")
     */
    protected $text;

    /**
     * @return integer $id
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * @return string $author
     */
    public function getAuthor()
    {
        return $this->author;
    }

    /**
     * @param string $author
     */
    public function setAuthor($author)
    {
        $this->author = $author;
    }

    /**
     * @return string $text
     */
    public function getText()
    {
        return $this->text;
    }

    /**
     * @param string $text
     */
    public function setText($text)
    {
        $this->text = $text;
    }
}

这是一个评论类

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="AppBundle\Repository\PostCommentRepository")
 */
class PostComment extends Comment
{
    /**
     * @ORM\ManyToOne(targetEntity="AppBundle\Entity\Post", inversedBy="comments")
     * @ORM\JoinColumn(nullable=true, onDelete="SET NULL")
     */
    private $post;

    /**
     * @ORM\OneToMany(targetEntity="AppBundle\Entity\ReplyComment", mappedBy="postComment", cascade={"remove"}, orphanRemoval=true)
     * @ORM\OrderBy({"id"="DESC"})
     */

    private $replyComments;

    /**
     * @return replyComment[] reply comments
     */
    public function getReplyComments()
    {
        return $this->replyComments;
    }

    /**
     * @param replyComment[] reply comments
     */
    public function setReplyComments($replyComments)
    {
        $this->replyComments = $replyComments;
    }

    /**
     * @return Post post
     */
    public function getPost()
    {
        return $this->post;
    }

    /**
     * @param Post post
     */
    public function setPost($post)
    {
        $this->post = $post;
    }
}

最后，这是控制器运行逻辑中的代码

if ($postCommentForm->isSubmitted() && $postCommentForm->isValid())
        {
            /** @var PostComment $comment */
            $comment = $postCommentForm->getData();
            $comment->setPost($post);

            $author = $this->getDoctrine()->getRepository('AppBundle:User')->findOneBy([
                'email' => $comment->getAuthor()
            ]);

            $comment->setAuthor($author);

            $em = $this->getDoctrine()->getManager();
            $em->persist($comment);
            $em->flush();

            return $this->redirectToRoute("single_post", [
                'id' => $post->getId()
            ]);
        }

---

首先，基类不需要是抽象的。相反，您必须在类上方插入此注释，以便doctrine将获得它：

@MappedSuperclass()

从基本实体中删除所有其他条令注释，所有注释都属于实体类

use Doctrine\ORM\Mapping as ORM;

/**
 *@MappedSuperclass()
 */
class Comment
{

和实体具有所有其他注释：

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="AppBundle\Repository\PostCommentRepository")
 * @ORM\Table(name="comment")
 */
class PostComment extends Comment
{

---

这应该会有帮助

然后您可以检查答案