Spring数据JPA从多对多关系删除问题

Question

在我的项目中，我使用Spring数据jpa。我有多对多关系的表格。我的实体：

    @Entity
    @Table(name = "SPEC")
    public class SpecJpa {
        @Id
        private int id;
        @Column(name = "NAME")
        private String name;
        @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
        @JoinColumn(name = "Creator_ID", unique = false, nullable = false, updatable = true)
        private UsersJpa usersJpa;
        @Column(name = "DESCRIPTION")
        private String description;


        @ManyToMany(fetch = FetchType.EAGER)
        @JoinTable(name="SPEC_PARTS",
                joinColumns = @JoinColumn(name="ID_PARTS", referencedColumnName="id"),
                inverseJoinColumns = @JoinColumn(name="ID_SPEC", referencedColumnName="id")
        )
    private Set<PartsJpa> partsJpa;
    //---------------

和零件：

@Entity
@Table(name = "PARTS")
public class PartsJpa {
    @Id
    private int id;
    @Column(name = "NAME")
    private String name;
    @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JoinColumn(name = "ID_EXPORT", unique = false, nullable = false, updatable = true)
    private ExportJpa exportJpa;
    @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JoinColumn(name = "ID_TYPE", unique = false, nullable = false, updatable = true)
    private TypesJpa typesJpa;

    @Column(name = "DESCRIPTION")
    private String description;

    @ManyToMany(fetch = FetchType.EAGER)

    private Set<SpecJpa> specJpa;

现在在Controller中，我尝试从表部分中删除一行：

@PostMapping("deletePart")
public String deletePart(@RequestParam String id, Model model) {
    partsService.deleteById(Integer.parseInt(id));
    return "redirect:/parts";

} 

但我有例外：

区分完整性约束冲突：“FK9Y4MKICYBLJWPENACP4298I49:PUBLIC.PARTS外键（ID\u导出）引用PUBLIC.EXPORT（ID）（1）”；SQL语句：/*删除com.aleksandr0412.demo.entitiesjpa。ExportJpa/delete from EXPORT where id=？[23503-200]]，SQL:/删除com.aleksandr0412.demo.entitiesjpa。ExportJpa*/delete from EXPORT where id=？2020-05-25 19:16:31.630警告13387---[nio-8080-exec-4]o.h.engine.jdbc.spi。SqlExceptionHelper:SQL错误：23503，SQLState:23503

在这个实体的数据库中，我有3个表：Parts、Spec和Spec\u Parts。据我所知，要解决这个问题，首先应该删除表spec_部分中的行，然后可以从表部分中删除行。我该怎么做？

Answer 1

在您的partsService实现中，我建议您首先使用给定的id从控制器获取要删除的资源（即PartsJpa）。接下来将其specJpa设置为null或emptySet，然后调用delete方法。

为此，请确保正确实现了方法setSpecJpa（SpecJpa SpecJpa）和setPartJpa（PartJpa PartJpa）。

我希望你觉得这有帮助。