php 了解 Doctrine 级联操作

Understanding Doctrine Cascade Operations

提问by Jasper N. Brouwer

I want to check my understanding of cascade operations on Doctrine associations. For the purpose of this question, I have two models: Customerand Insuree.

我想检查我对 Doctrine 关联级联操作的理解。出于这个问题的目的，我有两个模型：Customer和Insuree。

If I define a many to many relationship between a Customerand Insureeand set cascade{"all"}, I understand that this will:

如果我定义了一个许多人之间一对多的关系Customer，并Insuree与集cascade{"all"}，我明白，这将：

• Adding a new insuree to a customer will persist this insuree and create an association in the join table.
• Removing an insuree from the collection will detach the insuree from the customer and detach the customer from the insuree.
• Deleting the customer will delete all insurees associated with the customer.

• 向客户添加新的被保险人将保留此被保险人并在连接表中创建关联。
• 从集合中移除被保险人将使被保险人与客户分离，并将客户与被保险人分离。
• 删除客户将删除与该客户关联的所有被保险人。

This is the definition of the association on Customers.

这是 上关联的定义Customers。

/**
 * @ORM\ManyToMany(targetEntity="Insuree", inversedBy="customers", cascade={"all"})
 * @ORM\JoinTable(name="customer_insuree",
 *      joinColumns={@ORM\JoinColumn(name="customer_id", referencedColumnName="id")},
 *      inverseJoinColumns={@ORM\JoinColumn(name="insuree_id", referencedColumnName="id")}
 * )
 */
protected $insurees;

If I define the inverse many to many relationship between an Insureeand Customerand set cascade{"all"}, I understand that this will:

如果我定义了逆许多人的之间有很多关系Insuree，并Customer与集cascade{"all"}，我明白，这将：

• Adding a new customer to an insuree will persist this customer and create an association in the join table.
• Removing a customer from the collection will detach the customer from the insuree and detach the insuree from the customer.
• Deleting the insuree will delete all customers associated with it.

• 向被保险人添加新客户将保留该客户并在连接表中创建关联。
• 从集合中移除客户将使客户与被保险人分离，并将被保险人与客户分离。
• 删除被保险人将删除与其关联的所有客户。

This is the definition of the association on Insurees.

这是 上关联的定义Insurees。

/**
 * @ORM\ManyToMany(targetEntity="Customer", mappedBy="insurees", cascade={"all"})
 */
protected $customers;

If I then define the relationship as to cascade on persist, merge and detach - deleting the insuree will not delete all associated customers - it will only remove the associations between the insuree and its customers?

如果我然后将关系定义为级联持久、合并和分离 - 删除被保险人不会删除所有关联的客户 - 它只会删除被保险人与其客户之间的关联？

/**
 * @ORM\ManyToMany(targetEntity="Customer", mappedBy="insurees", cascade={"persist", "merge", "detach"})
 */
protected $customers;

回答by Jasper N. Brouwer

persist & remove

坚持和删除

You are correct about cascade={"persist"}meaning that persisting entity A, Doctrine will also persist all B entities in the Collection.

您是正确的cascade={"persist"}意思是持久化实体 A，Doctrine 也将持久化集合中的所有 B 实体。

You are also correct about cascade={"remove"}meaning that removing entity A, Doctrine will also remove all B entities in the Collection.
But I doubt you would ever want to use this on a ManyToMany association, because when you remove entity A that cascades this operation to all B entities, those B entities might be associated to other A entities.

您也正确地cascade={"remove"}表示删除实体 A，Doctrine 也将删除集合中的所有 B 实体。
但我怀疑您是否想在多对多关联上使用它，因为当您删除将这个操作级联到所有 B 实体的实体 A 时，这些 B 实体可能与其他 A 实体相关联。

detach & merge

分离与合并

You are notcorrect about cascade={"detach"}and cascade={"merge"}:

你对和 的看法不正确：cascade={"detach"}cascade={"merge"}

Adding/removing entities from the Collection is something youneed to do (in your code). Read about that here.

从集合中添加/删除实体是您需要做的事情（在您的代码中）。在这里阅读。

Detachmeans that you detach an entity from the EntityManager. The EntityManager will no longer manage that entity. This makes a detached entity the same as a newly instantiated entity, except that it's already in the database (but you made the EntityManager unaware of that).

分离意味着您从 EntityManager 分离实体。EntityManager 将不再管理该实体。这使得分离的实体与新实例化的实体相同，除了它已经在数据库中（但您让 EntityManager 不知道这一点）。

In other words: cascade={"detach"}means that detaching entity A, Doctrine will also detach all B entities in the Collection.

换句话说：cascade={"detach"}意味着分离实体A，Doctrine也会分离集合中的所有B实体。

Mergeis the opposite of detach: You will merge a detached entity back into the EntityManager.
Do note that merge()will actually return a newmanaged object, the detached object you passed to it remains unmanaged.

Merge与detach相反：您将分离的实体合并回 EntityManager。
请注意，merge()这实际上会返回一个新的托管对象，您传递给它的分离对象仍然是非托管的。