@MappedSuperclass and @OneToMany
-
22-10-2019 - |
문제
I need association OneToMany from Country to superclass Place (@MappedSuperclass). It could be bidirectional. I wolud need something like @OneToAny...
@MappedSuperclass
public class Place {
private String name;
private Country country;
@Column
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@ManyToOne
@JoinColumn(name="country_id")
public Country getCountry() {
return country;
}
public void setCountry(Country country) {
this.country = country;
}
}
Country:
@Entity
public class Country {
private long id;
private String name;
private List<Place> places;
@Any(metaColumn = @Column(name = "place_type"), fetch = FetchType.EAGER)
@AnyMetaDef(idType = "integer", metaType = "string", metaValues = {
@MetaValue(value = "C", targetEntity = City.class),
@MetaValue(value = "R", targetEntity = Region.class) })
@Cascade({ org.hibernate.annotations.CascadeType.ALL })
//@JoinColumn(name="unnecessary")
//@OneToMany(mappedBy="country") // if this, NullPointerException...
public List<Place> getPlaces() {
return places;
}
//and rest of class
Without @JoinColunm there is exception
Caused by: org.hibernate.AnnotationException: @Any requires an explicit @JoinColumn(s): tour.spring.bc.model.vo.Country.places
In table City and Region is foreign key to table Country (Region.country_id, City.country_id) which is ok. But I do NOT need foreign key in table Country to tables Region and City so I don't need @JoinColum.
I was looking for solution a lot but it seems there is no good solution.
해결책
@Any
doesn't make sense here since foreign key is at the Place
s side and therefore it doesn't need additional meta column.
I'm not sure if it's possible to create a polymorphic relationship to @MappedSuperclass
. However, you can try to declare Place
as @Entity @Inheritance(InheritanceType.TABLE_PER_CLASS)
, it should produce the same database schema and allow polymorpic relationship.