Question

当我尝试在实体中存在的方法中访问Lazy加载的@oneToMany关系属性时，出现以下错误。

错误：

Caused by: Exception [EclipseLink-7097] (Eclipse Persistence Services - 2.6.3.v20160428-59c81c5): org.eclipse.persistence.exceptions.ValidationException
Exception Description: Operation not supported: [instantiateForUnitOfWorkValueHolder].
    at org.eclipse.persistence.exceptions.ValidationException.operationNotSupported(ValidationException.java:1496)
    at org.eclipse.persistence.internal.indirection.ProtectedValueHolder.instantiateForUnitOfWorkValueHolder(ProtectedValueHolder.java:61)
    at org.eclipse.persistence.internal.indirection.UnitOfWorkValueHolder.instantiateImpl(UnitOfWorkValueHolder.java:160)
    at org.eclipse.persistence.internal.indirection.UnitOfWorkValueHolder.instantiate(UnitOfWorkValueHolder.java:234)
    at org.eclipse.persistence.internal.indirection.DatabaseValueHolder.getValue(DatabaseValueHolder.java:89)
    at org.eclipse.persistence.indirection.IndirectList.buildDelegate(IndirectList.java:271)
    at org.eclipse.persistence.indirection.IndirectList.getDelegate(IndirectList.java:455)
    at org.eclipse.persistence.indirection.IndirectList$1.<init>(IndirectList.java:597)
    at org.eclipse.persistence.indirection.IndirectList.listIterator(IndirectList.java:596)
    at org.eclipse.persistence.indirection.IndirectList.iterator(IndirectList.java:555)
    at com.order.modelGroupBase.getStatus(GroupBase.java:205)

实体：

@Entity
@Table(name="GROUP")
@Customizer(GroupBaseCustomizer.class)
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@ClassExtractor(GroupClassExtractor.class)
@InstantiationCopyPolicy
@Cacheable
@Cache( alwaysRefresh=true,
refreshOnlyIfNewer=true,
expiry=300000,      
coordinationType = CacheCoordinationType.SEND_NEW_OBJECTS_WITH_CHANGES)
public class GroupBase {

@OneToMany(cascade=CascadeType.ALL, mappedBy="groupBase", targetEntity=Groups.class)
@PrivateOwned
private List groups = new ArrayList<>();

public OrderGroupStatus getStatus() {

//error is at this line when I try to iterate..
for (Iterator itr = getGroups().iterator(); itr.hasNext();) {
    Groups relationship = (Groups) itr.next();
    //some operation..

    }           


}

}

我已经在eclipselink论坛上看过了，但他们没有明确地解决这个问题，有些链接说它与编织有关。但是在我的应用程序中我还没有编织所有，我也不打算这样做。

此代码适用于没有JPA的Eclipselink 2.3.2。现在我将Eclipselink 2.6.3与JPA 2.0和IBM Websphere 8.5.5.8结合使用。

注意：此问题不是每次都是随机发生的，也是在我创建新对象的时候发生的。

Answer 1

经过多次命中和修改我的延迟加载设置后，我发现在其他实体的同一实体上使用不同的fetchType会导致SHARED_CACHE模式下出现此问题。

entities

默认情况下@OneToMany是延迟提取的，但是在同一个实体的另一个实体中提供了＆＃39; Groups＆＃39;我已将fetchType配置为EAGER。

当我将两种获取类型都发送到LAZY时，此错误停止发生。

Eclipselink：不支持操作：[instantiateForUnitOfWorkValueHolder]

1 个答案: