Eclipselink：不支持的操作：[instantiateForUnitOfWorkValueHolder]

Question

当我尝试访问实体中存在的方法中延迟加载的@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.<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..

    }           


}

}

我在 eclipselink 论坛上看过，但他们没有明确解决这个问题，一些链接说它与我的应用程序中的 weaving.But 有关，我根本没有启用编织，我也没有不打算做。

此代码在没有 JPA 的 Eclipselink 2.3.2 上运行良好。现在，我将 Eclipselink 2.6.3 与 JPA 2.0 和 IBM Websphere 8.5.5.8 一起使用。

注意：这个问题不是每次都会随机发生，而且我观察到每次创建新对象时都会发生。

Answer 1

经过多次尝试并更正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 可能会在 SHARED_CACHE 模式下导致此问题。

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

默认情况下，@OneToMany 是延迟获取的，但在同一实体的另一个实体中 'Groups' 我已将 fetchType 配置为 EAGER。

当我将两种提取类型都设置为 LAZY 时，此错误不再发生。

Eclipselink：不支持的操作：[instantiateForUnitOfWorkValueHolder]

Eclipselink : Operation not supported: [instantiateForUnitOfWorkValueHolder]

lazy-loading

eclipselink

jpa-2.0