Question

我正在使用汽车和人表之间的休眠一对一映射。但是一个人可能有车，也可能没有车。现在，当使用休眠条件从人员表中获取记录时，我只想获取拥有汽车的人员，即人员表中仅存在对应于汽车表中条目的那些条目。如何使用休眠条件/别名来做到这一点？

下面是一段代码。请协助获取结果的标准或别名：

@Getter
@Setter
@Entity
@Table(name = "Person")
public class Person implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "Person_ID")
    private Long personId;

    @OneToOne(mappedBy = "personAsset", cascade = CascadeType.ALL)
    private Car car;
}

@Getter
@Setter
@Entity
@Table(name = "Car")
public class Car implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "Car_ID")
    private Long carId;

    @OneToOne
    @JoinColumn(name = "Person_ID")
    private Person personAsset;
}

Answer 1

您正在寻找的是orphanRemoval=true注释上的cascadeType @OneToOne。

您的课程如下所示：

@Getter
@Setter
@Entity
@Table(name = "Car")
public class Car implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "Car_ID")
    private Long carId;

    @OneToOne(fetch=FetchType.EAGER , cascade=CascadeType.ALL, orphanRemoval=true)
    @JoinColumn(name = "Person_ID")
    private Person personAsset;
}

Answer 2

CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Person> query = cb.createQuery(Person.class);
Root<Person> person = query.from(Person.class);
Predicate predicate = cb.isNotNull(person.join("car"));
predicates.add(predicate );

休眠一对一条件获取

2 个答案: