如何用自定义查询和Hibernate映射实体属性

Question

我有EntityA和EntityB，它们具有一个从EntityA->EntityB的OneToMany关系。我想将EntityB作为属性包含到EntityA中。

@Data
@Entity
public class EntityA {

    private static final String QUERY = 
        "(SELECT b.* FROM entity_b_table b
          WHERE b.entity_a_id = id 
          ORDER BY b.created_at DESC 
          LIMIT 1)"

    @Id
    @GeneratedValue
    private UUID id;
    private String firstName;
    @Column(updatable = false)
    private LocalDateTime createdAt;

    // What is the best way to achive this?
    @ManyToOne
    @JoinColumnsOrFormulas({
        @JoinColumnOrFormula(formula = @JoinFormula(value = QUERY, referencedColumnName = "id")),
    })
    private EntityB entityB;
}

@Data
@Entity
public class EntityB {
    @Id
    @GeneratedValue
    private UUID id;
    private String lastName;
    @Column(updatable = false)
    private LocalDateTime createdAt;

    private UUID entityAId;
}

另一种解决方法是在方法中获取并设置该属性，但我的目标是在entity类中找到一个解决方案。有人有主意吗？谢谢

Answer 1

错误消息给出了解释。公式只能返回一列。

必须将b.*更改为b.id。