如何使用 Doctrine2 中的级联选项让关联实体自动持久化? [英] How to use the cascade option in Doctrine2 to have associated entities automatically persisted?

问题描述

谁能给我解释一下:

$user = new User();

/* why do I have to call Entity Comment while trying to insert into db?  */
$myFirstComment = new Comment();

$user->addComment($myFirstComment);

$em->persist($user);
$em->persist($myFirstComment);
$em->flush();

为什么在尝试插入数据库时​​必须调用实体注释?

Why do I have to call Entity Comment while trying to insert into db?

我有级联.

1. 这是否意味着如果我在用户实体中与其他人有 50 个关系实体我必须在尝试时手动调用每个关系更新/插入/删除?
2. 如果我必须手动完成所有操作，为什么会存在级联?

如果我必须手动调用所有这些关系，那么使用 Doctrine 有点愚蠢.

If I have to call all that relation manually it is kind of stupid to use Doctrine at all.

我不明白这个.任何帮助表示赞赏.

I do not get this. Any help is appreciated.

这与此有关:doctrine2、存在关系时无法插入数据库

推荐答案

要让 Doctrine 自动处理 User#comments 属性的持久性，您必须将级联设置为persist"操作.

To have Doctrine automatically handle the persistence of your User#comments property you have to set cascade to the "persist" operation.

级联(persist、remove、merge、all)选项使您能够省略...

The cascade ( persist, remove , merge, all ) option gives you the ability to ommit ...

$em->persist($myFirstComment);

... 例如，如果您在双向关系的反面正确设置了它.如果您使用级联删除"删除用户实体，它还可以自动删除 User#comments ！

... if you set it correctly on your inverse side of a bidirectional relation for example. It can also automatically remove User#comments if you remove a User entity with cascade "remove" !

示例:

/**
 * Bidirectional - One-To-Many (INVERSE SIDE)
 *
 * @OneToMany(targetEntity="Comment", mappedBy="author", cascade={"persist", "remove"})
 */
private $comments;

在 Transistive Persistence/Cascade Options 文档章节.

请记住:

Doctrine 只会检查关联的拥有方是否有变化.

仅对关联的反面所做的更改将被忽略.确保更新双向关联的双方(或至少是拥有方，从 Doctrine 的角度来看)

Changes made only to the inverse side of an association are ignored. Make sure to update both sides of a bidirectional association (or at least the owning side, from Doctrine’s point of view)

• OneToMany 关联从来都不是拥有方.
• 反面必须使用 OneToOne、OneToMany 或 ManyToMany 映射声明的 mappedBy 属性.mappedBy 属性包含所属方关联字段的名称
• 拥有方必须使用 OneToOne、ManyToOne 或 ManyToMany 映射声明的 inversedBy 属性.inversedBy 属性包含反向侧关联字段的名称.
• ManyToOne 始终是双向关联的拥有方.
• OneToMany 始终是双向关联的反面.

• OneToMany associations are never the owning side.
• The inverse side has to use the mappedBy attribute of the OneToOne, OneToMany, or ManyToMany mapping declaration. The mappedBy attribute contains the name of the association-field on the owning side
• The owning side has to use the inversedBy attribute of the OneToOne, ManyToOne, or ManyToMany mapping declaration. The inversedBy attribute contains the name of the association-field on the inverse-side.
• ManyToOne is always the owning side of a bidirectional association.
• OneToMany is always the inverse side of a bidirectional association.

此外:

如果您创建一个新的根实体(即 $user = new User() )，该实体还没有被学说管理(并且您不必调用persist如果您正确设置了级联选项，则在您的示例中的 $myFirstComment 上).

you only have to call persist if you create a new root entity ( i.e. $user = new User() ) which is not already managed by doctrine ( and you don't have to call persist on $myFirstComment in your example if you have set the cascade option correctly ).

否则你只需要在实体由于某种原因没有被分离时调用flush.

Otherwise you only have to call flush if the entity hasn't for some reason been detached.

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