Question

我们使用Wildfly 8.2，因此使用JEE 7，其功能为JPA 2.1 Loadgraphs。

假设我们有以下分层实体结构（缩写类）：

@Entity
public class IsEntity {
    @Id private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    private IsEntity parentIsEntity;

    @OneToOne(fetch = FetchType.LAZY)
    @JoinTable(name = "IS_SHOULD", joinColumns = { @JoinColumn(name = "IS_ID") },
        inverseJoinColumns = { @JoinColumn(name = "SHOULD_ID", unique = true) }, foreignKey = @ForeignKey(
                name = "FK_SHOULD_ID"),
        inverseForeignKey = @ForeignKey(name = "FK_IS_SHOULD"))
    private ShouldEntity    shouldEntity;
}

@Entity
@NamedEntityGraph(name = "withShouldParent", attributeNodes = { @NamedAttributeNode("parentShouldEntity") }),
public class ShouldEntity {
    @Id private Long id;

    @Column
    private String someProperty;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "PARENT_ID", foreignKey = @ForeignKey(name = "FK_SHOULD_PARENT"))
    private ShouldEntity parentShouldEntity;

    @OneToOne(mappedBy = "shouldEntity", fetch = FetchType.LAZY)
    @JoinTable(name = "IS_SHOULD", joinColumns = { @JoinColumn(name = "SHOULD_ID") },
        inverseJoinColumns = { @JoinColumn(name = "IS_ID", unique = true) }, foreignKey = @ForeignKey(
                name = "FK_IS_SHOULD"),
        inverseForeignKey = @ForeignKey(name = "FK_SHOULD_IS"))
    private IsEntity    isEntity;
}

这种结构背后的功能要求是，我们首先在＆＃34;应该＆＃34; -side建模层次结构，然后创建相应的＆＃34;是＆＃34;在这个过程中。

鉴于，我有以下实体：

IsEntity(id = 10, shouldEntityId = 20, parentIsEntity = null)
ShouldEntity(id = 20, isEntityId = 10, parentShouldEntity = null, someProperty = "firstShouldParent")
ShouldEntity(id = 21, isEntityId = null, parentShouldEntity = 20, someProperty = "firstShouldChild")

现在我执行以下两个查询：

entityManager.find(IsEntity.class, 10); // IsEntityQuery

EntityGraph loadGraph = entityManager.getEntityGraph("withShouldParent");
Map<String, Object> queryHints = new HashMap<>();
queryHints.put( "javax.persistence.loadgraph", loadGraph );
ShouldEntity loadedEntity = entityManager().find( ShouldEntity.class, 21, queryHints ) );

以下对查询对象的调用崩溃：

loadedEntity.getParentShouldEntity().getSomeProperty();

错误消息是：

java.lang.ClassCastException： de.somecompany.ShouldEntity _ $$ _ jvst757_14无法转换为 de.somecompany.ShouldEntity

如果我省略IsEntityQuery，则ShouldEntity及其父级已正确加载！因此看起来，如果加载图应该加载实体管理器已经看到的实体，那么第一级缓存（？）和JPA加载图似乎存在问题。恕我直言，实体经理应该足够聪明地意识到ShouldEntity(id=20)在查询IsEntity时只是懒得加载，并且必须按照加载图的描述急切地获取它。至少这是我从规范第3.7.4.2节中读到的内容：

如果属性是一对一或多对一关系，并且属性在属性节点中指定，即默认提取获取目标实体的图表

所以，我的问题基本上是：预期的行为，甚至可能在某处描述，它是Hibernate 4.3.7中的错误（与WildFly 8.2.0一起提供）还是JPA规范中缺少的一部分？< / p>

非常感谢任何澄清！

JPA Loadgraph和Caching - 未获取的属性

0 个答案: