如何在 JPA 中为 ElementCollection 的列创建外键？

Question

Given the following class model:

package demo;

import java.util.Map;
import java.util.Set;
import javax.persistence.*;

@Embeddable
class Address {
  String street;
}

@Embeddable
class AddressDetails {
  byte[] photo;
}

@MappedSuperclass
abstract class User {
  @Id Long id;
  @ElementCollection(fetch = FetchType.EAGER) Set<Address> addresses;
  @ElementCollection Map<Address, AddressDetails> addressDetails; // wanted: FK to addresses
}

@Entity
class Sub1 extends User {}

@Entity
class Sub2 extends User {}

I'm trying to tell JPA that addressDetails references rows from addresses . How can I do that?

This is the foreign key constraint that I'd like to convert to annotations :

ALTER TABLE sub1_address_details
    ADD CONSTRAINT FK_sub1_address_address_details
        FOREIGN KEY (sub1_id, address_id)
            REFERENCES sub1_addresses
            ON DELETE CASCADE;

This is the foreign key constraint that Hibernate generates currently:

    alter table vblife_pv.sub1_addresses 
       add constraint FKdm58cvoq5gqndtlpr4t7auyct 
       foreign key (sub1_id) 
       references sub1

I tried to add

@CollectionTable(joinColumns = {@JoinColumn(table = "addresses", referencedColumnName = "id")})

to addressDetails , but this does not change Hibernate's DDL output.

I'm using Hibernate 5.4.21.

Answer 1

If you really want that, you should probably use the following:

@Entity
@Table(name = "addresses")
public class UserAddress {
    @EmbeddedId
    UserAddressId id;
    @ManyToOne(LAZY)
    @JoinColumn(name = "address_id", insertable = false, updatable = false)
    Address address;
    @ManyToOne(LAZY)
    @JoinColumn(name = "user_id", insertable = false, updatable = false)
    User user;
    @OneToOne(mappedBy = "userAddress")
    AddressDetails details;
}
@Embeddable
public class UserAddressId {
    int addressId;
    int userId;
}
@Entity
@Table(name = "address_details")
public class AddressDetails {
    @EmbeddedId
    UserAddressId id;
    @OneToOne
    @JoinColumns({
    @JoinColumn(name = "user_id", referencedColumn = "user_id", insertable = false, updatable = false),
    @JoinColumn(name = "address_id", referencedColumn = "address_id", insertable = false, updatable = false)
    })
    UserAddress userAddress;
}