Doctrine2 - 无法删除具有单向oneToMany关系的实体 [英] Doctrine2 - Cannot delete an entity with a unidirectional oneToMany relation

问题描述

当尝试删除包含单向一对多关联的实体时，我得到外部约束违规。我有以下简单的课程：

I'm getting a foreign constraint violation when trying to delete an entity, containing unidirectional one-to-many associations. I have the following simple class:

class Dealer{

/**
 * @ManyToMany(targetEntity="Car", cascade={"persist", "remove"})
 * @JoinTable(name="dealer_cars",
 *      joinColumns={@JoinColumn(name="dealer_id", referencedColumnName="id")},
 *      inverseJoinColumns={@JoinColumn(name="car_id", referencedColumnName="id",
        unique=true)}
 *    )
 **/
  protected cars;
}

Car 在这种情况下，不应该包含与其所有者的关系（因此是单向关系）。如果我尝试删除包含与汽车相关联的经销商对象，我会遇到以下约束违规：

The Car object should not contain a relation to its owner in this case (hence the unidirectional relationship). If I try to delete a Dealer object containing associations to cars, I get the following constraint violation:

Cannot delete or update a parent row: a foreign key constraint fails 
(`application`.`dealer_cars`, CONSTRAINT `FK_E1BCEEEBC3C6F69F`
 FOREIGN KEY (`car_id`) REFERENCES `car` (`id`))'

如果我尝试删除经销商行手动从数据库表，但我认为使用cascade =删除的Doctrine将为我照顾这个。

I would get the same message if I tried to delete the dealer row manually from the database table, but I thought Doctrine, using cascade="remove", would take care of this for me.

如果我将关联更改为双向关联它工作。为什么这不适用于单向关联？

If I change the association to a bidirectional association it works. Why does this not work with unidirectional associations?

推荐答案

使用Doctrine的数据库级别onDelete选项

Use the Database level onDelete option with Doctrine

@ORM\JoinColumn(name="dealer_id", referencedColumnName="id",  onDelete="SET NULL")

来自此处的

解释：

explanation from here:

• 当父级更改时，CASCADE会传播更改。 （如果删除一行，引用该行的约束表中的行也将被删除等）。



• 当设置父列行时，SET NULL将列值设置为NULL

• CASCADE will propagate the change when the parent changes. (If you delete a row, rows in constrained tables that reference that row will also be deleted, etc.)

• SET NULL sets the column value to NULL when a parent row goes away.

RESTRICT导致父列的尝试DELETE失败。

RESTRICT causes the attempted DELETE of a parent row to fail.

... 更新您的数据库模式之前，抱怨它不工作： - ）

... update your database schema prior to complaining it's not working :-)

app/console doctrine:schema:update --force

如果由于外键错误而无法正常工作，那么（以这个顺序）：

if this is not working due to foreign key errors go the hard way (in this order) :

• 应用程序/ console doctrine：database：drop


• app / console doctrine：database：create


• app / console doctrine：schema：update --force
• 
  
• （可选：app / console doctrine：fixtures：load）

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