java - Hibernate中embedded member对成员的唯一约束

Question

是否可以在 Hibernate 中为嵌入式类的成员定义唯一约束？

我需要确保 Nested::i1 和 Nested::i2 作为一对(组合)是唯一的

@Entity
@Table( uniqueConstrains = ???)
public class Widget {
   @Id
   private int id;

   @Embedded
   Nested nested;
}

@Embeddable
public class Nested {
    private int i1;
    private int i2;
}

Answer 1

可以通过使用:

@Entity
@Table(uniqueConstraints = { @UniqueConstraint(columnNames = {"i1", "i2"})})
public class Widget {

这将导致 CREATE SQL(postgresql 示例)

create table Widget 
(  id int8 not null,
   i1 int8, 
   i2 int8 ,
   primary key (id),
   unique (i1, i2)
) 

可选 - 当您在一个文件中添加 @AttributeOverride 注释指定时，它可能会更简洁和可读 - 两个属性的列名

@AttributeOverrides({
        @AttributeOverride(name = "i1", column = @Column(name = "i1")),
        @AttributeOverride(name = "i2", column = @Column(name = "i2"))
})
@Embedded
Nested nested;