多个JQPL提取联接因Hibernate失败

Question

使用Hibernate 3.6.7和JPA 2，我在一个查询中不能有两个获取联接。 实体具有称为父对象的自引用字段。 localizedTexts是Java类型的Map的@ElementCollection 。 Entity.getParent（）具有一个带有EAGER加载策略的@ManyToOne。

这是实体的外观：

@Entity
public class Entity extends BaseEntity {
    /* ... */

    @ManyToOne(fetch = FetchType.EAGER)
    public Entity getParent() {
        return parent;
    }

    @ElementCollection
    @MapKeyColumn(name = "language")
    @Column(name = "text")
    public Map<String, String> getLocalizedTexts() {
        return localizedTexts;
    }

    /* ... */
}

以下两个查询有效：

select e from Entity e join fetch e.parent.localizedTexts

select e from Entity e join fetch e.localizedTexts

但这不起作用：

select e from Entity e join fetch e.localizedTexts join fetch e.parent.localizedTexts 

Hibernate抱怨： query specified join fetching, but the owner of the fetched association was not present in the select list [FromElement{explicit,collection join,fetch join,fetch non-lazy properties,classAlias=null,role=net.company.project.Entity.localizedTexts,tableName={none},tableAlias=localizedt3_,origin=null,columns={,className=null}}] [select e from net.company.project.Entity e join fetch e.localizedTexts join fetch e.parent.localizedTexts]

Answer 1

如果要预加载实体的“父”关联以及父代的“ localizedTexts”关联，则应声明以正确顺序遍历模型树的联接：

select e from Entity e join fetch e.parent p joint fetch p.localizedTexts