JPA：@Embeddable对象如何获得对其所有者的引用？ [英] JPA: How can an @Embeddable object get a reference to its owner?

问题描述

我有一个拥有@Embedded类Profile的User类。如何将配置文件的实例提交给其所有者User类？

  @Entity 
 class User implements可串行化{
 @Id @GeneratedValue（strategy = GenerationType.IDENTITY）
 private Integer id; 
 
 @嵌入式配置文件配置文件; 
 
 // ..其他属性.. 
} 
 
 @Embeddable 
 class Profile实现Serializable {
 
用户用户; //如何使这项工作？ 
 
 setURL（String url）{
 if（user.active（））{//这种用法
 //做某事
} 
} 
 
 // ..其他属性.. 
} 
  

@Embedded 应用于getter / setter对而不是私有成员本身。

  @Entity 
 class User实现Serializable {
 @Id @GeneratedValue（strategy = GenerationType.IDENTITY）
私人整数ID; 
 
 @Access（AccessType.PROPERTY）
 @Embedded 
私人个人资料个人资料; 
 
 public Profile getProfile（）{
 return profile; 
} 
 
 public void setProfile（Profile profile）{
 this.profile = profile; 
 this.profile.setUser（this）; 
} 
 
 // ... 
} 
  

<但是，在这种情况下，我会质疑一个嵌入式实体是否是您想要的，而不是@OneToOne关系，或者简单地将Profile类扁平化为User。 @Embeddable的主要基本原理是代码重用，在这种情况下似乎不太可能。

I have a User class that has @Embedded a class Profile. How can I give the instances of Profile a reference to their owner the User class?

@Entity
class User implements Serializable  {
   @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Integer id;

   @Embedded Profile profile;

   // .. other properties ..
}

@Embeddable
class Profile implements Serializable {

   User user; // how to make this work?

   setURL(String url) {
      if (user.active() ) { // for this kind of usage
         // do something
      }
   }

   // .. other properties ..
}

解决方案

Assuming JPA rather than strictly Hibernate, you might do this by applying @Embedded to a getter/setter pair rather than to the private member itself.

@Entity
class User implements Serializable {
   @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Integer id;

   @Access(AccessType.PROPERTY)
   @Embedded
   private Profile profile;

   public Profile getProfile() {
      return profile;
   }

   public void setProfile(Profile profile) {
      this.profile = profile;
      this.profile.setUser(this);
   }

   // ...
}

However, I would question whether an embedded entity is what you want at all in this case, as opposed to a @OneToOne relationship or simply "flattening" the Profile class into User. The main rationale for @Embeddable is code reuse, which seems unlikely in this scenario.

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