Hibernate Mapping - Joining two tables with an association table - But with a twist

Question

I have the following entities... Customer, Card and Address

Customer:

 {
     private String cust_id; // Primary k         


        

Answer 1

You could use the annotation @JoinTable after the @OneToOne to point the card's table, so you won't need an entity for card, but if the card's table isn't just a relational table, you could map card in User as @OneToOne and have a @Transient 'getAddress()' method that returns 'this.card.getAddress()', but on card's entity you must map the relation between Address and Card(@OneToOne(mappedBy='card_id')), and in Address you could map card_id as @Id.

First Alternative

Customer:

@OneToOne
@JoinTable(name="card", joinColumns = @JoinColumn(name="cust_id"),
inverseJoinColumns = @JoinColumn(name="card_id"))
private Address address;

Second alternative

Customer:

@OneToOne(mappedBy="cust_id")
private Card card;

...
@Transient
public Address getAddress(){
 return this.card == null ? null : this.card.getAddress();
}

Card:

@OneToOne(mappedBy="card_id")
private Address address;

Address:

@Id
private String card_id;

In the Second case Card has a Embedded pk which is formed by two fks(Customer and Address)

Card:

@EmbeddedId
private CustomerAddressPK id;

CustomerAddressPK

@Embeddable
public class CustomerAddressPK(){

  private String cust_id;
  private String card_id;
}