php - 使用 Doctrine 中的类表继承从子表中删除行

Question

我用两个模型做了一个非常基本的例子。

"Singer" extends from "Person"

我正在使用 class table Inheritance使用这两个模型:

<?php
namespace models;

/**
 * @Table(name="persons")
 * @entity
 * @InheritanceType("JOINED")
 * @DiscriminatorColumn(name="type", type="string")
 * @DiscriminatorMap({"singer" = "\models\Singer"})
 */
abstract class Person {

    /**
     * @Id
     * @Column(type="integer", nullable=false, name="id_person")
     * @GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /** @column(type="string", nullable=false) */
    protected $name;

歌手模型长这样:

namespace models;

/**
 * @Table(name="singers")
 * @entity
 */
class Singer extends Person{

    /** @column(type="string", nullable=false) */
    protected $gender;
}

工作流程

考虑这种情况。

1. 在数据库中我有这些行:

   人员表:

   id_person | name | type
   -----------------------
   1           john   singer
   

   歌 watch :

   id_person | gender
   ------------------
   1           pop  
   

2. 我继续删除这位歌手:

   $singer = $em->find('models\Singer', 1);
   $em->remove($singer);
   $em->flush();
   

3. 执行上面的代码后，我再次检查数据库，发现:

   人员表:

   id_person | name | type
   -----------------------
   (empty)
   

   歌 watch :

   id_person | gender
   ------------------
   1           pop  
   

   如您所见，子表中的行未按预期删除。

4. 因此，在搜索 doctrine 的文档后，它指出:

   When you do not use the SchemaTool to generate the required SQL you should know that deleting a class table inheritance makes use of the foreign key property ON DELETE CASCADE in all database implementations. A failure to implement this yourself will lead to dead rows in the database.

   所以，我继续修改 persons 表，如下所示:

   ALTER TABLE persons 
   ADD CONSTRAINT fk_persons_1
   FOREIGN KEY (id_person)
   REFERENCES singers (id_person)
   ON DELETE CASCADE
   ON UPDATE NO ACTION;
   

现在，问题变得复杂了:

• 当我删除歌手时，信息仍然存在，甚至 persons 表也被更改以便从歌 watch 中删除。

• 当我尝试插入一位新歌手时

  $singer = new \models\Singer('Zara', 'rock');
  $em->persist($singer);
  $em->flush();
  

  它抛出一个异常:

  Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`practica`.`persons`, CONSTRAINT `fk_persons_1` FOREIGN KEY (`id_person`) REFERENCES `singers` (`id_person`) ON DELETE CASCADE ON UPDATE NO ACTION)' in /var/www/html/doctrine/vendor/doctrine/dbal/lib/Doctrine/DBAL/Statement.php:138 Stack trace: #0 /var/www/html/doctrine/vendor/doctrine/dbal/lib/Doctrine/DBAL/Statement.php(138): PDOStatement->execute(NULL) #1 /var/www/html/doctrine/vendor/doctrine/orm/lib/Doctrine/ORM/Persisters/JoinedSubclassPersister.php(165): Doctrine\DBAL\Statement->execute() #2 /var/www/html/doctrine/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php(929): Doctrine\ORM\Persisters\JoinedSubclassPersister->executeInserts() #3 /var/www/html/doctrine/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php(318): Doctrine\ORM\UnitOfWork->executeInserts(Object(Doctrine\ORM\Mapping\ClassMetadata)) #4 /var/www/html/doctrine/vendor/doct in /var/www/html/doctrine/vendor/doctrine/dbal/lib/Doctrine/DBAL/DBALException.php on line 47
  

所以，基本上，我只需要删除 MySQL 数据库中子表中的信息。但是我不明白。

Answer 1

尝试反转FOREIGN KEY，即将它从你的 persons 表中删除并添加到你的 singers 表中

ALTER TABLE singers 
ADD CONSTRAINT fk_singers_1
FOREIGN KEY (id_person)
REFERENCES persons (id_person)
ON DELETE CASCADE
ON UPDATE NO ACTION;