Question

我正在尝试使用JPA和JSF-primefaces的Web项目。我有插入/更新具有@ManyToOne关系的对象的错误。

插入后，@ JoinColumn为空白字段。（抱歉，不发布图片，这是图片链接）

然后，在重新加载列表后，空白字段恢复正常

我正在使用单向@ManyToOne实体

Place.java

@Entity
@Table(name = "place")
@XmlRootElement

public class Place implements Serializable {
   private static final long serialVersionUID = 1L;
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   @Basic(optional = false)
   @Column(name = "id")
   private Integer id;
   ...
   @Basic(optional = false)
   @NotNull
   @Column(name = "prefecture_id")
   private int prefectureId;

   @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
   @JoinColumn(name = "prefecture_id",referencedColumnName = "id", updatable = false,insertable = false)
   private Aken prefecture;

Aken.java

@Entity
@Table(name = "aken")
@XmlRootElement
public class Aken implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @NotNull
    @Column(name = "id")
    private Short id;
    @Size(max = 50)
    @Column(name = "data")
    private String data;

方法更新到数据库

@Stateless
@TransactionManagement(TransactionManagementType.BEAN)
public class PlaceFacade extends AbstractFacade<Place> {
    @PersistenceContext(unitName = "JutenPU")
    private EntityManager em;

    @Resource
    private UserTransaction userTransaction;

    public void edit(Place place){
      try{
          getUserTransaction().begin();
          getEntityManager().merge(place);
          getUserTransaction().commit();
          }catch(Exception e){
            System.out.println(e.getMessage());
          }
      }

方法检索表

上的数据

public List<Place> findAll() {
    javax.persistence.criteria.CriteriaQuery cq =   getEntityManager().getCriteriaBuilder().createQuery();
    cq.select(cq.from(Place.class));
    return getEntityManager().createQuery(cq).getResultList();
}

我正在使用JAVA EE7，glassfish服务器4，primefaces 4.0

感谢您的帮助

Answer 1

@JoinColumn(name = "prefecture_id",referencedColumnName = "id", updatable = false,insertable = false)

您将外键列标记为READONLY。

删除限制：@JoinColumn(name = "prefecture_id",referencedColumnName = "id")

JPA：插入后的数据表不显示@joincolumn @ManyToOne

1 个答案: