带3个外键的休眠表
问题描述:
我试图将下表映射到实体。带3个外键的休眠表
@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,我从数据库中获取的所有数据,但是当我尝试存储具有工作的新事件,分配给它的工具我得到错误。
当event2work2instrumentation表中的字段配置为不为空时,我得到:字段没有默认值。
如果我给外地的默认值,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?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event2work2指令的引用。
答
的解决方案是使用地图和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<>();
答
尝试截断两个表,然后存储新的FK。它发生在我身上时,我有一个object_related_id这是不是在对象表作为一个id
我不是专家,但你可能需要向'@ManyToMany()'添加'cascade = CascadeType.INSERT'或'cascade = CascadeType.ALL'。 – qtips