Question

我想从实体预订中删除行。这个实体看起来像

@Entity
@Table(name="reservation")
public class Reservation {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true)
    private Integer id;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @OnDelete(action = OnDeleteAction.CASCADE)
    @JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
    private Seance reservationSeance;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "user_id")
    private User userReservation;

    @OneToMany(orphanRemoval = true)
    private List<Seat> seats = new ArrayList<>();
    ............

}

和我的曲目

@Entity
@Table(name="repertoire")
@Data
public class Repertoire {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true)
    private Integer id;

    @ManyToMany(cascade = {CascadeType.ALL})
    @JoinTable(
            name = "repertoire_seance",
            joinColumns = { @JoinColumn(name = "repertoire_id")},
            inverseJoinColumns = {@JoinColumn(name = "seance_id")}
    )
    List<Seance> seances = new ArrayList<>();
   ......

}

现在我有错误

Cannot delete or update a parent row: a foreign key constraint fails (`todo`.`repertoire_seance`, CONSTRAINT `FKani6veaxbp3vxruqjivg9o9sp` FOREIGN KEY (`seance_id`) REFERENCES `seance` (`id`))

我在实体关系ManyToMany中和休眠状态创建了附加表repertoire_seance。

如何避免从Seance表中删除记录，我只希望从Reservartion表中删除记录？

Answer 1

您尚未发布Seance和repository代码，因此我会填补空白。

首先，您需要删除@OnDelete(action = OnDeleteAction.CASCADE)注释，因为它实际上是在删除Seance时告诉数据库删除Reservation。

然后，您需要在Reservartion表的外键列（@JoinColumn）中允许空值，如下所示：

@Entity
@Table(name="Seance")
public class Seance {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true)
    private Integer id;

    @OneToMany(fetch = FetchType.LAZY)
    @JoinColumn(name = "reservation_id", nullable = true)
    private Reservation reservation;

    ...
}

最后，在您的DAO中，您需要为与要删除的Seance相关的Reservation设置空值，然后才将其删除，如下所示：

public void deleteReservation(int reservationId) {
    Session currentSession = sessionFactory.getCurrentSession();

    // get reservation with primary key
    Reservation reservation = currentSession.get(Reservation.class, reservationId);  
    Seance seance = reservation.getSeance();

    //set reservation_id null
    Seance.setReservation(null);

    //delete the reservation
    currentSession.remove(reservation);
}

删除约束行

1 个答案: