Hibernate creating entry but not setting FK in @OneToOne

Question

I do have 2 entitys, which are connected via @OneToOne annotation. First my classes for better understanding:

2nd Entity:

@Table(name = "REASON_FOR_CLIENT_CHEQUE_PAYMENT_REVERSAL")
@Entity
public class ReversalReason implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 3338809410372872259L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer code;

    private boolean tax;
    private boolean currency;
    private boolean amountChange;
    private boolean locationChange;
    private boolean recipient;
    private boolean period;

    public ReversalReason() {

    }
}

Base entity:

@Table(name = "CLIENT_CHEQUE_PAYMENT")
@Entity
public class ClientChequePayment extends BaseDomainObject implements Serializable {
    /** Serial version UID */
    private static final long serialVersionUID = -1988633355L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer code;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "code", nullable = true)
    private ReversalReason reasonForReversal;

    @Column(nullable = true, length = 50)
    private String proposeReversalUser;
    @Column(length = 50, unique = true)
    private String displayCode;
    @Column(length = 50)
    private String originalEntry;

    private PaymentStatus originalPaymentStatus;

I did ommit some fields because otherwise the code would be too much. Now lets go to the problem:

In my program I want to be able to set the field reasonForReversal of ClientChequePayment with calling session.update(clientChequePayment);. I checked if the field was set before calling update and it was. The problem is, that hibernate does create a entry for ReversalReason, but it does not set the PK of ReversalReason as FK in ClientChequePayment entry. Because of that, i can create several ReversalReason enries for 1 ClientChequePayment.

Is my mapping correct (I have no need to acces ClientChequePayment via ReversalReason, but vice versa)? Should the mapping be bi-directional even tho its not needed?

Answer 1

Continuing from the comments.

That's the problem, you need a column that has a foreign key to REASON_FOR_CLIENT_CHEQUE_PAYMENT_REVERSAL.

Meaning, your table CLIENT_CHEQUE_PAYMENT needs a foreign key to REASON_FOR_CLIENT_CHEQUE_PAYMENT_REVERSAL, something like id_reversal_reason and then you can do:

@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "id_reversal_reason", nullable = true)
private ReversalReason reasonForReversal;

The join column is on the owning table for source table.

A snippet from name from the @JoinColumn javadocs:

(Optional) The name of the foreign key column.
 * The table in which it is found depends upon the
 * context.
 * <ul>
 * <li>If the join is for a OneToOne or ManyToOne
 *  mapping using a foreign key mapping strategy,
 * the foreign key column is in the table of the
 * source entity or embeddable.