多对多关系删除操作面临的问题

Question

模特：客户

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "client_discipline_relation",
joinColumns = @JoinColumn(name = "client_id", referencedColumnName = "id"),
inverseJoinColumns = @JoinColumn(name = "discipline_id", referencedColumnName = "id"))
private Set<ClientDiscipline> disciplines = new HashSet<>();

模型：ClientDiscipline

@ManyToMany(mappedBy = "disciplines")
private Set<Client> clients;

当我删除一个 clientDiscipline 时，我会执行以下操作

clientService.removeDiscipline(disciplineService.findById(disciplineId),client.getId());
disciplineService.delete(disciplineId);

删除代码：

@Override
    @Transactional(readOnly = false)
    public void removeDiscipline(ClientDiscipline discipline, Long id) {
        Client client=findClientById(id);
        Set<ClientDiscipline> existingDisciplines=client.getDisciplines();
        if(existingDisciplines.contains(discipline)) {
            existingDisciplines.remove(discipline);
        }
        client.setDisciplines(existingDisciplines);
        clientRepository.save(client);
    }

删除代码：

@Override
    @Transactional(readOnly = false)
    public void delete(Long id) {
        Preconditions.checkNotNull(id);
        disciplineRepository.delete(id);
    }

删除操作执行well.it删除学科。但是在控制台日志中抛出如下异常

Hibernate: delete from disciplines where id=?
 WARN [http-bio-8080-exec-2] (org.hibernate.engine.jdbc.spi.SqlExceptionHelper) - SQL Error: 1451, SQLState: 23000
ERROR [http-bio-8080-exec-2] (org.hibernate.engine.jdbc.spi.SqlExceptionHelper) - Cannot delete or update a parent row: a foreign key constraint fails (`hcs_zabzorg`.`client_discipline_relation`, CONSTRAINT `FKtqmvkwvwlxjgi4acfgriqk2ei` FOREIGN KEY (`discipline_id`) REFERENCES `disciplines` (`id`))
ERROR [http-bio-8080-exec-2] (org.hibernate.internal.ExceptionMapperStandardImpl) - HHH000346: Error during managed flush [org.hibernate.exception.ConstraintViolationException: could not execute statement]

该行从 database.though 中删除，我可以删除，所以这不是问题，但为什么会出现此异常以及如何解决知道的人吗？

Answer 1

尝试使用 clientRepository.saveAndFlush(client) 来刷新对联接 table 所做的更改。

Answer 2

手动清除 many to 关系解决了这个问题。由于我不使用任何 CASCADE 类型或孤立删除，因此必须手动清除多对多字段/

public class Discipline extends Person {

    private static final long serialVersionUID = 431537630160539107L;

    @ManyToOne
    @JoinColumn(name = "relation")
    private ClientRelation relation;


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


    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "client_disciplines",
            joinColumns = @JoinColumn(name = "discipline_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(name = "client_id", referencedColumnName = "id"))
    private Set<Client> clients = new HashSet<>();

    @Column(name = "hasPermission")
    private boolean hasPermission = false;



    public Discipline(Company company) {
        super(company);
    }


}

@Override
    @Transactional(readOnly = false)
    public void delete(Long id) {
        Preconditions.checkNotNull(id);
        Discipline discipline=findById(id);
        discipline.getClients().clear();
        
        disciplineRepository.delete(discipline);
    }

多对多关系删除操作面临的问题

problem faced with many to many relation delete operation

many-to-many

hibernate

jpa

delete-row