级联删除实体在多对多关系中不起作用

deleting entities in cascade not working in ManyToMany relation(级联删除实体在多对多关系中不起作用)

问题描述

我有一个父实体类别和一个子实体文章.它们由 ManyToMany 关系定义.一篇文章可以标记在一个或多个类别中，每个类别可以标记在多个文章中.

I have a parent entity Category and a child entity Article. They are defined by a ManyToMany relation. One article can be taged in one or more category and every Category can be tagged in more than one Article.

我想做什么
我希望当我删除一个类别时，该类别中标记的每篇文章也会被删除，但前提是它们没有被其他类别标记.

WHAT I TRY TO DO
I would like that when I delete a Category, every Article tagged in the Category are also deleted BUT only if they are not tagged by an other Category.

我已经测试过的内容
我测试了 2 个类别(id=1 和 id=2)和两篇文章(id=71 和 id=91).第 71 条同时具有第 1 类和第 2 类.第 91 条仅与第 2 类相关.
因此，在删除第 2 类时，我希望删除第 91 条而不是第 71 条(因为这一篇仍然与 category_1 链接)

WHAT I HAVE ALREADY TESTED
I tested with 2 category (id=1 and id=2) and with two articles (id=71 and id=91). article 71 has both category 1 and 2. Article 91 is linked only with category 2.
So when deleting category 2 I expect to delete article 91 but not article 71 (as this one is still linked with category_1)

但是无论我尝试什么都没有发生...

But none of this happenned whatever I tried...

在下图中，我总结了使用不同策略(1/cascade={"remove"}、2/orphanRemoval=true 和 3/ondelete="级联").
绿色从数据库中删除.

In the following picture I summed up what I get using different strategies (1/cascade={"remove"} , 2/orphanRemoval=true and 3/ondelete="CASCADE" ).
In green the removal from the database.

我的代码(部分代码)

在控制器中

public function deleteCategory(Category $category)
{
  $em = $this->getDoctrine()->getManager();
  $em->remove($category);
  $em->flush();
}

对于策略 1/cascade={"remove"}

 // IN CLASS/ENTITY CATEGORY - OWNER OF THE RELATION
 * @ORMManyToMany(targetEntity="Article", inversedBy="categories",  cascade={ "remove"})
 private $articles;

 // IN CLASS/ENTITY ARTICLE 
 * @ORMManyToMany(targetEntity="Category", mappedBy="articles")
 private $categories;

对于策略 2/orphanRemoval=true

 // IN CLASS/ENTITY CATEGORY - OWNER OF THE RELATION
 * @ORMManyToMany(targetEntity="Article", inversedBy="categories",  orphanRemoval=true)
 private $articles;

 // IN CLASS/ENTITY ARTICLE 
 * @ORMManyToMany(targetEntity="Category", mappedBy="articles")
 private $categories;

对于策略 3/onDelete="CASCADE"

 // IN CLASS/ENTITY CATEGORY - OWNER OF THE RELATION
 * @ORMManyToMany(targetEntity="Article", inversedBy="categories")
 private $articles;

 // IN CLASS/ENTITY ARTICLE 
 * @ORMManyToMany(targetEntity="Category", mappedBy="articles")
 * @ORMJoinColumn(onDelete="CASCADE")

 private $categories;

我的问题

除了我已经尝试过的 3 种策略或者必须在控制器中完成这些删除之外，还有其他方法吗?

is there some other way of doing it but the 3 strategies I already tried or those removals have to be done in the controller?

推荐答案

据我所知，您不能仅使用级联功能来做到这一点.

You can't do this using just cascading features as far as I can think of.

一个干净的解决方案是创建一个订阅 preRemove 事件的侦听器.然后，您可以检查某个类别何时被删除，并查找该类别中没有任何其他类别的所有文章并将其删除.

A clean solution would be to create an listener which subscribes to the preRemove events. You can then check when a category is deleted and find all articles from that category which do not have any other categories and remove those as well.

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