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问题描述



例如:
$ b




$ b我想了解如何最好地实现hibernate中的多态一对多。 $ b

  @MappedSuperclass 
公共类BaseEntity {
整数id;
//等等...
}

@Entity
public class作者extends BaseEntity {}

@Entity
公共类Post扩展BaseEntity {}

@Entity
public class Comment BaseEntity {}

现在,我还想坚持审计信息,与以下类:

  @实体
public class AuditEvent {
@ManyToOne //?
BaseEntity实体;

$ / code>

auditEvent.entity ?另外,Hibernate会如何坚持下去?会生成一系列连接表( AuditEvent_Author AuditEvent_Post AuditEvent_Comment
注意,我宁愿没有其他实体类暴露连接的另一端(例如, BaseEntity )上列出< AuditEvent>事件 - 但如果这是最简洁的实现方式,那就足够了。 / p>

解决方案

映射超类不是实体,因此不能成为关联的一部分(如)。所以:


  • 使您的 BaseEntity 摘要并使用 TABLE_PER_CLASS 策略(请参阅此)

  • 在层次结构中引入另一个 AuditableEntity 实体,并使用最为您的用例提供适当的继承策略。

  • 考虑使用

I'm trying to understand how to best implement a polymorphic one-to-many in hibernate.

Eg:

@MappedSuperclass
public class BaseEntity  {
    Integer id;
    // etc...
}

@Entity
public class Author extends BaseEntity {}

@Entity
public class Post extends BaseEntity {}

@Entity
public class Comment extends BaseEntity {}

And now, I'd like to also persist audit information, with the following class:

@Entity
public class AuditEvent {
    @ManyToOne // ?
    BaseEntity entity;
}

What is the appropriate mapping for auditEvent.entity? Also, how will Hibernate actually persist this? Would a series of join tables be generated (AuditEvent_Author , AuditEvent_Post, AuditEvent_Comment), or is there a better way?

Note, I'd rather not have my other entity classes expose the other side of the join (eg., List<AuditEvent> events on BaseEntity) - but if that's the cleanest way to implement, then it will suffice.

解决方案

A mapped superclass is not an entity and thus can't be part of an association (as reminded in EJB-199). So either:

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07-26 01:18