OneToOne Mapping with hibernate/JBoss/Seam

Question

Hello,

I want to create a one to one mapping between the Entity Customer and OptIn. The OptIn Entity is optional. That is why the foreign key must be in OptIn. At deployment I get the following error because the mapping can not be found:

OneToOneSecondPass.java:135

Values: otherSide= optIn, mappedBy=customer

otherSideProperty = BinderHelper.findPropertyByName( otherSide, mappedBy );

java.lang.NullPointerException at org.hibernate.cfg.OneToOneSecondPass.doSecondPass(OneToOneSecondPass.java:135) at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1130) at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:296) at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1115) ...

What can I do to get a correct mapping?

@Entity
@Table(name = "KPS_OPT_IN", schema = "EB")
public class OptIn extends KmsEntity implements java.io.Serializable {

    private static final long serialVersionUID = -8818445355079384264L;


    private int id; /* kps_kunden_nr */

    private Customer customer;  

    public OptIn() {
    }

    @Id
    @Column(name = "KPS_KUNDEN_NR", unique = true, nullable = false) 
    public int getId() {
     return this.id;
    }

    public void setId(int id) {
     this.id = id;
    }

    @OneToOne
    @PrimaryKeyJoinColumn(name="KPS_KUNDEN_NR", referencedColumnName="KPS_KUNDEN_NR") 
    public Customer getCustomer() {
     return customer;
    }

    public void setCustomer(Customer customer) {
        this.customer = customer;
        this.setId(customer.getId());
    }    
}

---

@Entity
@Table(name = "KPS_KUNDEN", schema = "EB")
public class Customer extends KmsEntity implements java.io.Serializable {

    private static final long serialVersionUID = 1L;

    private int id; 

    private OptIn optIn;

    public Customer() {
    }

    public Customer(int id) {
     this.id = id;
    }

    @Id
    @GeneratedValue(generator="seqkpskunde")
    @SequenceGenerator(name="seqkpskunde",sequenceName="SEQ_KPS_KUNDE") 
    @Column(name = "KPS_KUNDEN_NR", unique = true, nullable = false)
    public int getId() {
     return this.id;
    }

    public void setId(int id) {
     this.id = id;
     if(optIn!=null){
      optIn.setId(id);
     }
    }

    @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "customer")
    public OptIn getOptIn() {
     return optIn;
    }

    public void setOptIn(OptIn optIn) {
     this.optIn = optIn;
    }
}

Answer 1

I'm not sure what you mean by "foreign key must be in OptIn". You've mapped your @OneToOne association via @PrimaryKeyJoinColumn which means your entities will be linked via their ID values. It also means that:

1. You can't specify column names within @PrimaryKeyJoinColumn annotation; they will be taken from appropriate @Id columns on both entities instead.
2. Marking fetch as LAZY is pointless and going to be ignored; optional @OneToOne associations are always eagerly fetched.
3. The only way OptIn would be optional on this association is if there was no entry with given ID in the database.

What Hibernate / Annotations versions are you using? If they're rather old it could be a bug in Hibernate code. But I believe it should work if you fix (1) and (2) above.