symfony - 与额外字段的多对多自关系？

Question

我正在尝试开发一个 friend 系统，我需要在我的用户实体上建立多对多关系；现在，这就是我所做的:

/**
 * @ORM\ManyToMany(targetEntity="User", mappedBy="friends")
 */
protected $friendsWith;

/**
 * @ORM\ManyToMany(targetEntity="User", inversedBy="friendsWith")
 * @JoinTable(name="friends",
 *            joinColumns={@JoinColumn(name="user_id", referencedColumnName="id")},
 *            inverseJoinColumns={@JoinColumn(name="friend_user_id", referencedColumnName="id")}
 *           )
 */
protected $friends;

但是我想为这些关系添加一些额外的字段，例如创建日期或状态(已接受、待处理，...)；我创建了另一个实体“Friend”，我希望该实体用作 friend 之间的链接。但我真的不知道如何管理这个......

你有什么想法吗？

谢谢!

Answer 1

恐怕您需要额外的类(class)才能建立这样的关联。以下是学说文档中的提示:

Why are many-to-many associations less common? Because frequently you want to associate additional attributes with an association, in which case you introduce an association class. Consequently, the direct many-to-many association disappears and is replaced by one-to-many/many-to-one associations between the 3 participating classes.

http://www.doctrine-project.org/docs/orm/2.1/en/reference/association-mapping.html#many-to-many-unidirectional

我想应该是 friend -> 特殊关联类(包含字段:user_id、friend_id、创建日期) -> friend 。并且您将 Friend 关联到两个字段 $myFriends 和 $imFriendOf 中的特殊类:)