当我开始使用JPA时,我已经看到错误“ org.hibernate.TransientPropertyValueException:对象引用了一个未保存的临时实例-在刷新之前保存该临时实例”。我知道一般可以通过添加cascade = CascadeType.ALL来解决此错误,但是在这种情况下,此错误已出现在域表中,这意味着在这种情况下,将CascadeType放置没有任何意义,因为该实体已经具有数据库中的ID。
我的代码的相关部分是(还有其他字段,getter,setter等):
Rac类:
@Entity
@Table(name = "RAC", schema = "SchRAC")
public class Rac {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "RacCod")
private Long idRac;
//anoter fields (...)
@OneToMany(fetch = FetchType.LAZY, mappedBy = "rac", cascade = {CascadeType.ALL})
@JsonManagedReference
private List<RacProvidencia> racProvidencias;
RacProvidencia类:
@Entity
@Table(name = "RACPRO", schema = "SchRAC")
public class RacProvidencia implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "RacProCod")
private Long idRacProvidencia;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "RacCod")
@JsonBackReference //coloquei para evitar a recursao infinita de JSON
private Rac rac;
@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.REFRESH)
@JoinColumn(name = "ProCod")
private Providencia providencia;
@NotNull
@Column(name = "RacProNum", length = 100)
private String numero;
@Column(name = "RacProDat")
private Date dataProvidencia;
Providencecia类(域表):
@Entity
@Table(name = "PRO", schema = "SchRAC")
public class Providencia {
@Id
@Column(name = "ProCod")
private Integer idProvidencia;
@Column(name = "ProDes", length = 50)
private String descricao;
服务:
public RacProvidencia adicionarProvidenciaRac(Long codigo, @Valid RacProvidencia racProvidencia) {
Rac rac = this.racRepository.findById(codigo).get();
racProvidencia.setRac(rac);
return racProvidenciaRepository.save(racProvidencia);
}
如您所见,对象“ Rac”已经保存,然后用户添加“ Providencias”(如果愿意)。然后,我收到对象“ Providencia”,按ID搜索对象Rac,设置对象并保存。
此错误最奇怪的部分是因为5分钟后,系统不再显示此错误。可能会发生什么?将来如何避免这个问题?
答案 0 :(得分:1)
您具有双向关系,但只设置了关系的一侧。
public RacProvidencia adicionarProvidenciaRac(Long codigo, @Valid RacProvidencia racProvidencia) {
Rac rac = this.racRepository.findById(codigo).get();
racProvidencia.setRac(rac);
rac.getRacProvidencias().add(racProvidencia); // <-- This
return racProvidenciaRepository.save(racProvidencia);
}
您的持久性提供者双方都需要。