带3个外键的休眠表

Question

我试图将下表映射到实体。

的事件表的映射是这样的：

@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。

Answer 1

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<>(); 

Answer 2

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