如何在jpa中连接多个主键或特定主键的列

Question

@Entity
@Table(name = "A")
public class A {
    @Id
    @Column(name = "id")
    private Long id;

    @Id
    @Column(name = "name")
    private String name;

    @JoinColumn(name = "test_id")
    private List<Test> testId;
}

@Entity
@Table(name = "Test")
public class Test {
    @Id
    @Column(name = "test_id")
    private Long testId;
}

错误结果为

“OneToOne关系的JPA问题：外键引用的列数错误。应为2”

如何为join测试表指定主键？

表A：列id与表B：列test_id映射

Answer 1

由于您的表a有一个复合键，您应该将列分离到另一个键类中，然后连接到表的键的单独部分。

例如，创建akey

@Embeddable
public class AKey {

    @Column(name = "id")
    private Long id;

    @Column(name = "name")
    private String name;

    //getters and setters
}

然后替换类A中的ID

@Entity
@Table(name = "A")
public class A {
    @EmbeddedId
    private AKey key;

    @JoinColumn(name = "test_id")
    private List<Test> testId;
}

然后可以在test.testid=a.key.id上执行联接