堅持@OneToMany名單

Question

我試圖堅持以下幾點：

@Entity 
@Table(name="tb_father") 
public class Father implements Serializable { 

private static final long serialVersionUID = 1L; 

@Id 
@SequenceGenerator(name = "tb_father_id_seq", sequenceName = "tb_father_id_seq") 
@GeneratedValue(strategy = GenerationType.AUTO, generator = "tb_father_id_seq") 
@Column(name = "id", nullable = false) 
private Integer id; 

@OneToMany(fetch = FetchType.LAZY, mappedBy="father", cascade = {CascadeType.PERSIST, CascadeType.MERGE}) 
private List<Son> sons; 

... Gets and Sets 

} 


@Entity 
@Table(name="tb_son") 
public class Son implements Serializable { 

private static final long serialVersionUID = 1L; 

@Id 
@SequenceGenerator(name = "tb_son_id_seq", sequenceName = "tb_son_id_seq") 
@GeneratedValue(strategy = GenerationType.AUTO, generator = "tb_son_id_seq") 
@Column(name = "id", nullable = false) 
private Integer id; 

@Inject 
@ManyToOne(fetch=FetchType.LAZY) 
@JoinColumn(name="father", referencedColumnName="id") 
private Father father; 


... Gets and Sets 

} 

例子：

Father father = new Father(); 
Son son = new Son(); 
... 
father.getSons().add(son); 

在我FatherDAO

@Stateless 
public class FatherDAO { 

    @PersistenceContext(unitName = "test") 
    private EntityManager em; 

    @TransactionAttribute(TransactionAttributeType.MANDATORY) 
    public void persistFatherSons(Father father) throws ApplicationException { 
     try { 
      em.persist(father); 
     } catch(Exception e) { 
     ... 
     } 
    } 

... 

} 

表：

CREATE TABLE tb_father 
(
    id integer NOT NULL, 
    CONSTRAINT tb_father_pkey PRIMARY KEY (id), 
) 

CREATE TABLE tb_son 
(
    id integer NOT NULL, 
    father integer, 
    CONSTRAINT tb_son_pkey PRIMARY KEY (id), 
    CONSTRAINT fk41b1efcfa0ebdd8c FOREIGN KEY (father) 
     REFERENCES tb_father (id) MATCH SIMPLE 
) 

運行「em.persist（父）」時，只有父親保存在數據庫中，而不是兒子（列表）。現在

錯誤：

08:00:21,123 WARN [com.arjuna.ats.arjuna] (http--10.36.1.49-8180-1) ARJUNA012125: TwoPhaseCoordinator.beforeCompletion - failed for SynchronizationImple< 0:ffff7f000101:-81b794d:5523b2cf:61, org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization@6bb7796b >: javax.persistence.PersistenceException: error during managed flush 
at org.hibernate.ejb.AbstractEntityManagerImpl$CallbackExceptionMapperImpl.mapManagedFlushFailure(AbstractEntityManagerImpl.java:1486) [hibernate-entitymanager-4.0.1.Final.jar:4.0.1.Final] 
... 

就緒！這兩個實體ai是我創建的示例，用於演示此處正在發生的問題。該示例中缺少的是Float字段。該字段爲@ Size並且這是導致錯誤的原因。

Thankssss

Answer 1

請嘗試以下更改。

@Inject 
@ManyToOne(fetch=FetchType.LAZY) 
@JoinColumn(name="father") 
private Father father;