java Hibernate正在@OneToOne中创建条目但未设置FK

Question

我有两个实体，它们通过@OneToOne注释连接。首先，为了更好地理解我的课程：

第二实体：

@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() {

    }
}

基本实体：

@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;

我对一些字段进行了ommit，因为否则代码会太多。现在让我们来看问题：

在我的程序中，我希望能够通过调用session.update(clientChequePayment);来设置reasonForReversal的ClientChequePayment字段。我检查了在调用update之前是否设置了该字段，结果是。问题是，hibernate确实为ReversalReason创建了一个条目，但它没有将ReversalReason的PK设置为ClientChequePayment条目中的FK。因此，我可以为1ClientChequePayment创建几个ReversalReasonenries

我的映射正确吗（我不需要通过ReversalReason访问ClientChequePayment，反之亦然）？即使不需要，映射是否应该是双向的

Answer 1

继续评论

这就是问题所在，您需要一个列，该列具有指向REASON_FOR_CLIENT_CHEQUE_PAYMENT_REVERSAL的外键

也就是说，表CLIENT_CHEQUE_PAYMENT需要一个外键来REASON_FOR_CLIENT_CHEQUE_PAYMENT_REVERSAL，类似于id_reversal_reason，然后您可以执行以下操作：

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

联接列位于源表的所属表上

来自@JoinColumnjavadocs的name的片段：

(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.