带有@OneToMany属性的可嵌入实体 [英] Embeddable entity with @OneToMany attribute

问题描述

假设我有以下实体：

  @Entity 
 public class A {
 @Id 
 @GeneratedValue 
私人长ID; 
 
 @Embedded 
 private B b; 
 
 // getters and setters 
} 
 
 @Embeddable 
 public class B {
 @OneToMany 
 private List< C> ; CLIST; 
 // getters和setters 
} 
 
 @实体
公共类C {
 @Id 
 @GeneratedValue 
 private Long ID; 
 //其他字段，getters和setters 
} 
  

使用模式自动生成功能与 Hibernate 我得到一个额外的表，其中包含 A 和 C 。但我想通过将 A 的 id 添加到 C 中来实现一对多关系。 code>（例如没有附加表格）。

这可能吗？如果是的话，我应该使用什么样的注释来创建这样的映射？

通常情况下，@JoinColumn 注释。

  @OneToMany 
 @JoinColumn（name =A_ID）
 private列表与LT c取代; CLIST; 
  

如果您对可嵌入列中的A_ID名称不满意，则可以在实体中覆盖列名A：

  @AssociationOverride（name =cList，
 joinColumns = @JoinColumn（name =SOME_NAME_FOR_JOIN_COLUMN_IN_TABLE_C） ）
 @Embedded 
 private B b; 
  

Say, I have following entities:

@Entity
public class A {
  @Id
  @GeneratedValue
  private Long id;

  @Embedded
  private B b;

  //getters and setters
}

@Embeddable
public class B {
  @OneToMany
  private List<C> cList;
  //getters and setters
}

@Entity
public class C {
  @Id
  @GeneratedValue
  private Long id;
  //other fields, getters and setters
}

Using schema-autogeneration feature with Hibernate I get an additional table which contains mappings between A and C. But I'd like to implement a one-to-many relationship by adding A's id into C (e.g without additional table).

Is this possible? If yes, what annotations should I use to create such a mapping?

解决方案

In general that is possible with @JoinColumn annotation. It works also with embeddables.

@OneToMany
@JoinColumn(name="A_ID")
private List<C> cList;

If you are not happy with A_ID name for column given in embeddable, you can override column name in entity A:

@AssociationOverride(name= "cList",
        joinColumns = @JoinColumn(name="SOME_NAME_FOR_JOIN_COLUMN_IN_TABLE_C"))
@Embedded
private B b;

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