Question

我有一个spring mvc应用程序，用户可以在其中预定会议室。当我尝试通过使用deleteById（）删除预订时，属于该预订的用户也会被删除。我该如何预防？

预订对象：

package spe_booker.models;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import java.util.Date;
@Entity
public class Booking {
    @Id
    @GeneratedValue
    private Long id;
    @NotNull
    private Date startDateTime;
    @NotNull
    private Date endDateTime;
    @NotNull
    @ManyToOne(cascade = CascadeType.ALL)
    private Room room;
    @NotNull
    @ManyToOne(cascade = CascadeType.ALL)
    private User user;
    private Date creationDate;

    public Booking() {  }
    ...getters and setters...

用户对象：

package spe_booker.models;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
@Entity
@Table(name = "user")
public class User {
    @Id
    @GeneratedValue
        private Long id;
    private String username;
    String name;
    private String password;
    private String faculty;
    private String role;
    private Boolean blacklisted;
    @Column(name = "enabled")
    public int enabled;
    @OneToMany(mappedBy = "user")
    private List<Booking> bookings = new ArrayList<>();
    ...getters and setters...

预订资料库：

package spe_booker.Repositorys;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import spe_booker.models.Booking;
import spe_booker.models.User;

import java.util.List;

@Repository
public interface BookingRepository extends CrudRepository<Booking, Long> {
    List<Booking> findAll();
    List<Booking> findBookingsByUser(User user);
}

删除呼叫：

bookingRepository.deleteById(id);

Answer 1

更改

的级联

@NotNull
@ManyToOne(cascade = CascadeType.ALL)
private User user;

设置为适当的值。您是否更改用户，然后同时保存预订和用户？您是否同时与用户创建预订？如果您可以用“否”回答这些问题，则可以完全删除(cascade = CascadeType.ALL)。并且您应该问自己为什么级联首先出现！

Answer 2

CascadeType.ALL强制JPA层叠所有操作（持久，删除，更新...）。也就是说，当您删除/更新预订时，它也会同时删除/更新房间和用户对象

删除子级时，如何防止JPA deleteByID（）删除父级？

2 个答案: