hibernate表有3个外键

Question

我试图将下表映射到实体。

事件表的映射如下所示：

@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer _id;
@Column(name = "title")
private String _title;
@Column(name = "description")
private String _description;
@Column(name = "location")
private String _place;
@Column(name = "start")
private Date _start;
@Column(name = "end")
private Date _stop;
@Column(name = "points")
private int _points;
@Enumerated(EnumType.STRING)
@Column(name = "type")
private EventType _eventtype;

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "event2work2instrumentation", joinColumns = {
        @JoinColumn(name = "event")},
        inverseJoinColumns = {@JoinColumn(name = "work")})
private Set<WorkMapper> _works = new HashSet<>(0);

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "event2work2instrumentation", joinColumns = {
        @JoinColumn(name = "event")},
        inverseJoinColumns = {@JoinColumn(name = "instrumentation")})
private Set<InstrumentationMapper> _instrumentations = new HashSet<>(0);

它工作正常，我从数据库中获取所有数据，但是当我尝试存储一个分配了工作和工具的新事件时，我会收到错误。

当event2work2instrumentation表中的字段配置为不为null时，我得到：field没有默认值。

如果我给出字段默认值，我得到：

SQLIntegrityConstraintViolationException: Cannot add or update a child row:
    a foreign key constraint fails (`schema`.`event2work2instrumentation`, CONSTRAINT `e2w2i_instrumentation_fk` FOREIGN KEY (`instrumentation`) REFERENCES `instrumentation` (`id`))

你有什么想法吗？它可能取决于仪器和/或工作的映射吗？这些类在其映射中没有对event2work2instrumentation的引用。

Answer 1

尝试截断两个表，然后存储新的FK。当我有一个object_related_id并且在对象表中没有作为id

时，它发生在我身上

Answer 2

解决方案是使用map和MapKeyJoinColumn注释：

@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@JoinTable(name = "event2work2instrumentation", joinColumns = {
        @JoinColumn(name = "event")},
        inverseJoinColumns = {@JoinColumn(name = "instrumentation")})
@MapKeyJoinColumn(name = "work")
private Map<WorkMapper, InstrumentationMapper> _eventToWorkAndInstrumentationMappers = new HashMap<>();