级联中的实体删除不能在ManyToMany关系中工作 [英] deleting entities in cascade not working in ManyToMany relation

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。一篇文章可以在一个或多个类别中进行，每个类别都可以被标记在多个文章中。

我要做什么 br>
当我删除一个类别时，我想要的是，类别中标记的每个文章也被删除，但只有当它们没有被其他类别标记时。

我已经测试了什么

我用2个类别（id = 1和id = 2）和两个文章（id = 71和id = 91）进行了测试。
第71条同时属于第1类和第2类。第91条仅与第2类相关联。

因此，删除第2类时，我希望删除第91条但不删除第71条（因为这仍然是与类别1相关联）

但是，没有一个发生在我尝试过的任何事情...

在我总结了使用不同的策略（1 / cascade = {remove}，2 / orphanRemoval = true和3 / ondelete =CASCADE）。
下面的图片 >
在 绿色 中删除数据库。

我的代码（代码部分）

控制器

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

策略1 / cascade = {删除 }

  // IN CLASS / ENTITY CATEGORY  - 拥有者关系
 * @ ORM\ManyToMany（targetEntity =Article，inversedBy =categories，cascade = {remove}）
 private $ articles; 
 
 // IN CLASS / ENTITY ARTICLE 
 * @ ORM\ManyToMany（targetEntity =Category，mappedBy =articles）
 private $ categories; 
  

为策略2 / orphanRemoval = true

  // IN CLASS / ENTITY CATEGORY  - 所有者的关系
 * @ ORM\ManyToMany（targetEntity =文章，inversedBy =categories，orphanRemoval = true）
 private $ articles; 
 
 // IN CLASS / ENTITY ARTICLE 
 * @ ORM\ManyToMany（targetEntity =Category，mappedBy =articles）
 private $ categories; 
  

策略3 / onDelete =CASCADE em>

  // IN CLASS / ENTITY CATEGORY  - 所有者的关系
 * @ ORM\ManyToMany（targetEntity =Article，inversedBy =categories）
 private $ articles; 
 
 // IN CLASS / ENTITY ARTICLE 
 * @ ORM\ManyToMany（targetEntity =Category，mappedBy =articles）
 * @ ORM\JoinColumn（onDelete =CASCADE）
 
 private $ categories; 
  

我的问题

还有其他一些方法，但是我已经尝试过的3种策略或者这些移除必须在控制器中完成？

解决方案

只要我能想到，您就不能使用级联功能。

一个干净的解决方案是创建一个预订 preRemove 事件的监听器。
然后，您可以检查一个类别是否被删除，并查找该类别中没有其他类别的所有文章，并删除这些类别。

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.

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.

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)

But none of this happenned whatever I tried...

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.

MY CODE (PART OF CODE)

in the controller

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

for strategy 1/ cascade={"remove"}

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

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

for strategy 2/ orphanRemoval=true

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

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

for strategy 3/ onDelete="CASCADE"

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

 // IN CLASS/ENTITY ARTICLE 
 * @ORM\ManyToMany(targetEntity="Category", mappedBy="articles")
 * @ORM\JoinColumn(onDelete="CASCADE")

 private $categories;

MY QUESTION

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?

解决方案

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

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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