JPA继承IdClass [英] JPA Inheritence IdClass

问题描述

如何在多重继承实体复合键的情况下使用IdClass?

How to use IdClass in multiple inheritance entity composite key case ?

    @IdClass(IdClassEntity1.class)
    class Entity1 {
    private long e1pk1;
    private long e1pk2;
    }
    @IdClass(IdClassEntity2.class)
    class Entity2 extends Entity1  {
    private long e2pk1;
    private long e2pk2;
    }
    class Entity3 extends Entity2 {
    private long e3pk1;
    private long e3pk2;
    }

IdClassEntity2应该是什么:

what should be IdClassEntity2 :

class IdClassEntity2 {
        private long e1pk1;
        private long e1pk2;
        private long e2pk1;
        private long e2pk2;
}

或

class IdClassEntity2 {
        private IdClassEntity1 idClassEntity1;
        private long e2pk1;
        private long e2pk2;
}

推荐答案

您可以使用@MappedSuperClass或@Entity声明@IdClass. pk通过继承传播.

You can use a @MappedSuperClass or @Entity to declare the @IdClass. The pk is propagated via inheritance.

例如，使用@MappedSuperClass，您可以执行以下操作:

For example, using @MappedSuperClass, you can do the following:

@MappedSuperClass
@IdClass(IdClassEntity1.class)
public class Entity1 {
    @Id private long e1pk;    
    @Id private long e1pk;
    ...

 @Entity
 public class Entity2 extends Entity1 {
    ...

使用@Entity，遵循相同的范例

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