Java CriteriaBuilder加入 - 無法解決或不是字段

Question

我試圖做一個選擇使用CriteriaBuilder加入，但我在Eclipse中出現此錯誤。我該如何解決它？

Hibernate version: hibernate-jpa-2.0-api<br /> 

Java Version: 1.8 

fonte cannot be solved or is not a field 

NotificacaoDao.java

@Stateless 
public class NotificacaoDao { 
    @PersistenceContext(unitName = "PostgreSQLDS") 
    private EntityManager em; 

    @EJB 
    private NotificacaoDao NotificacaoDao; 

    public List<Notificacao> getResultList(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, Object> filters) throws ApplicationException{ 
     try { 

      CriteriaBuilder cb = em.getCriteriaBuilder(); 
      CriteriaQuery<Notificacao> cq = cb.createQuery(Notificacao.class); 

      Metamodel m = em.getMetamodel(); 
      EntityType<Notificacao> Notificacao_ = m.entity(Notificacao.class); 

      Root<Notificacao> myObj = cq.from(Notificacao_); 
      Join<Notificacao, Fonte> fontes = myObj.join(Notificacao_.fonte); // HERE I'M GETTING THE ERROR 
      cq.where(NotificacaoDao.getFilterCondition(cb, myObj, filters)); 
      Predicate filterCondition = NotificacaoDao.getFilterCondition(cb, myObj, filters); 
      filterCondition = cb.and(filterCondition, cb.equal(myObj.get("excluido"), "N")); 
      cq.where(filterCondition); 
      if (sortField != null) { 
       if (sortOrder == SortOrder.ASCENDING) { 
        cq.orderBy(cb.asc(myObj.get(sortField))); 
       } else if (sortOrder == SortOrder.DESCENDING) { 
        cq.orderBy(cb.desc(myObj.get(sortField))); 
       } 
      } 
      return em.createQuery(cq).setFirstResult(first).setMaxResults(pageSize).getResultList(); 
     } catch(Exception e) { 
      throw new ApplicationException("myException", e); 
     } 
    } 

Notificacao.java

@Entity 
@Table(name = "tb_notificacao", schema = "indicadores") 
@NamedQuery(name = "Notificacao.findAll", query = "SELECT n FROM Notificacao n") 
@FilterDef(name="notificacaoNaoExcluido", defaultCondition="excluido = 'N'") 
public class Notificacao implements Serializable { 
    private static final long serialVersionUID = 1L; 

    @Id 
    @SequenceGenerator(name = "tb_notificacao_codnotificacao_seq", sequenceName = "TB_NOTIFICACAO_CODNOTIFICACAO_SEQ", schema = "indicadores", allocationSize = 1) 
    @GeneratedValue(generator = "tb_notificacao_codnotificacao_seq") 
    @Column(name = "codnotificacao", nullable = false) 
    private Integer codnotificacao; 

    private String descricao; 

    private String excluido; 

    private String nome; 

    // bi-directional many-to-one association to CargaNotificacao 
    @OneToMany(mappedBy = "notificacao") 
    private List<CargaNotificacao> cargaNotificacoes; 

    // bi-directional many-to-one association to Fonte 
    @Inject 
    @ManyToOne 
    @JoinColumn(name = "codfonte") 
    private Fonte fonte; 

    // bi-directional many-to-one association to UsuarioNotificacao 
    @OneToMany(mappedBy = "notificacao") 
    @Filter(name="usuarioNaoExcluido", condition="excluido = 'N'") 
    private List<UsuarioNotificacao> usuarioNotificacoes; 

    public Notificacao() { 
    } 
    // getters and setters 
} 

Fonte.java

@Entity 
@Table(name = "tb_fonte", schema = "indicadores") 
@NamedQuery(name = "Fonte.findAll", query = "SELECT f FROM Fonte f") 
public class Fonte implements Serializable { 
    private static final long serialVersionUID = 1L; 

    @Id 
    @SequenceGenerator(name = "tb_fonte_codfonte_seq", sequenceName = "TB_FONTE_CODFONTE_SEQ", schema = "indicadores", allocationSize = 1) 
    @GeneratedValue(generator = "tb_fonte_codfonte_seq") 
    @Column(name = "codfonte", nullable = false) 
    private Integer codfonte; 

    private String nome; 

    // bi-directional many-to-one association to Indicador 
    @OneToMany(mappedBy = "fonte") 
    @Filter(name="indicadorNaoExcluido", condition="excluido = 'N'") 
    private List<Indicador> indicadores; 

    // bi-directional many-to-one association to Notificacao 
    @OneToMany(mappedBy = "fonte") 
    @Filter(name="notificacaoNaoExcluido", condition="excluido = 'N'") 
    private List<Notificacao> notificacoes; 

    public Fonte() { 
    } 
    // getters and setters 
} 

Answer 1

好了，元模型基本上有使用三種方法：

1. 使用IDE根據元模型生成工具
2. 使用靜態規範元模型類
3. 使用em.getMetamodel（）API即您使用之一。

我建議你用更接近你在做什麼是第三點

3點解決方案解決方案： 替換下面的代碼：

Metamodel m = em.getMetamodel(); 
    EntityType<Notificacao> Notificacao_ = m.entity(Notificacao.class); 
    Root<Notificacao> myObj = cq.from(Notificacao_); 
    Join<Notificacao, Fonte> fontes = myObj.join(Notificacao_.fonte); // HERE I'M GETTING THE ERROR 

隨着新代碼：

Metamodel m = em.getMetamodel(); 
    EntityType<Notificacao> notificacao_ = m.entity(Notificacao.class); 
    Root<Notificacao> myObj = cq.from(notificacao_); 
    Join<Notificacao, Fonte> fontes = myObj.join(notificacao_.getSingularAttribute("fonte",Fonte.class)); 

積分1 & 2解決方案 請注意Notificacao_必須是靜態或生成的類，並且絕不能是em.getMetamodel（）的實例。你的情況還要注意前Notificacao_是一個變量，而不是一類，如下所示：

EntityType<Notificacao> Notificacao_ = m.entity(Notificacao.class); 

如果您需要更多的信息，讓我知道吧。