java - 保存关系的一侧时出现 LazyInitializationException

Question

我有一个 Patient 类，其中包含 Id 集合和文件夹集合。当我尝试单独保存文件夹时，由于患者的 id 集合，它会抛出 LazyInitializationException。

患者类别如下所示:

@Entity
@Table(name = "patient")
public class Patient implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Long id;

    @OneToMany(mappedBy = "patient", fetch = FetchType.LAZY, orphanRemoval = true, cascade = CascadeType.ALL)
    private Set<Id> ids = new HashSet<Id>();

    @OneToMany(mappedBy = "patient", fetch = FetchType.LAZY, orphanRemoval = true, cascade = CascadeType.ALL)
    private List<Folder> folders = new ArrayList<Folder>();

    ...
}

文件夹类如下所示:

@Entity
@Table(name = "folder")
public class Folder implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "patient_id", referencedColumnName = "id")
    private Patient patient;

}

然后我有一个服务类，它可以执行一些操作，然后保存一个像这样的文件夹:

@Override
@Transactional
public void importData(Data data) {

    // do other things
    Folder folder = new Folder();
    // initialize folder values
    ...
    folder.setPatient(patient);
    folderDAO.save(folder);
    ...
}

当它尝试将文件夹保存在FolderDAO中时:

getHibernateTemplate().saveOrUpdate(folder);

它抛出:

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: es.mycompany.myapp.Patient.ids, could not initialize proxy - no Session
    at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:587)

Answer 1

使用cascade = ALL配置，您正在配置hibernate以在保存文件夹实体时更新患者列表/组，患者列表必须加载到内存中才能更新。您也许可以尝试删除 CASCADE = ALL 并手动管理任何列表和一组患者类别更新。