查询指定连接提取，但提取关联的所有者不在选择列表中

Question

我选择了两个 id 列，但指定了错误：

org.hibernate.QueryException: **query specified join fetching, but the owner of the fetched association was not present in the select list** 

[FromElement{explicit,not a collection join,fetch join,fetch non-lazy properties,classAlias=r,role=null,tableName=REVISIONS,tableAlias=revision1_,origin=ENTITY_CHANGED_IN_REVISION entitychan0_,columns={entitychan0_.REV_ID ,className=ru.csbi.registry.domain.envers.Revision}}] [ select ec.id as entityChangeId, r.id as revisionId from ru.csbi.registry.domain.envers.EntityChange as ec  inner join fetch ec.revision as r  where ec.groupEntityId = :groupEntityId and ec.groupName = :groupName  and r.timestamp < :entityDateFrom  and r.timestamp > :entityDateTo  and (        ec.revisionType in (0, 5, 1, 4, 2 )       and not ( ec.otherGroupEntityModified = false and ec.thisGroupEntityModified = true and ec.rowDataModified = false and ec.collectionOfNotGroupEntityModified = false   )      )  group by ec.id, r.id  having count(*) > :start order by r.id desc]

一些代码：

String hql = " select ec.id as entityChangeId, r.id as revisionId from EntityChange as ec " +
            " inner join fetch ec.revision as r " +
            " where ec.groupEntityId = :groupEntityId" +
            " and ec.groupName = :groupName " +
            " and r.timestamp < :entityDateFrom " +
            " and r.timestamp > :entityDateTo " +
            " and ( " +
            "       ec.revisionType in (" + 
                        RevisionType.ADD.getRepresentation() + ", " + 
                        RevisionType.ONLY_DATA_PROPERTY_MOD.getRepresentation() + ", " +
                        RevisionType.BOTH_COLLECTION_AND_PROPERTY_MOD.getRepresentation() + ", " +
                        RevisionType.ONLY_COLLECTION_PROPERTY_MOD.getRepresentation() + ", " +
                        RevisionType.DEL.getRepresentation() +
                    " ) " +
            "     and not ( "+
                    "ec.otherGroupEntityModified = false and " +
                    "ec.thisGroupEntityModified = true and " +
                    "ec.rowDataModified = false and " +
                    "ec.collectionOfNotGroupEntityModified = false " +
                "  ) " +
            "     ) " +
            " group by ec.id, r.id " +
            " having count(*) > :start" +
            " order by r.id desc";

如何修复错误，我做错了什么？

Answer 1

使用常规join而不是join fetch （顺便说一下，默认情况下它是inner的）：

String hql = " select ec.id as entityChangeId, r.id as revisionId from EntityChange as ec " + 
        " join ec.revision as r " + ...

正如错误消息告诉你的那样， join fetch在这里没有意义，因为它是一个强制加载集合的性能提示。

Answer 2

由于您需要join fetch ，因此删除fetch将无法满足您的需求。

您应该做的是与它一起指定一个计数查询。

假设您正在对结果进行分页，下面是一个以 id 作为param的 JPA 查询，它将导致您指定的问题，第二个查询通过向其添加计数查询来解决此问题。

注意： fk_field是tableA中具有一对多rln 的属性。 count 查询不使用join fetch 。

@Query(value = "from TableA a LEFT JOIN FETCH a.fk_field where a.id = :id") 

@Query(value = "from TableA a LEFT JOIN FETCH a.fk_field where a.id = :id", 
  countQuery = " select  count(a) from TableA a left join a.fk_field where a.id = :id")
       

Answer 3

您必须将相关项目列放入选择子句

select ec.id as entityChangeId, r.id as revisionId, **r.revision** 
from EntityChange as ec " +
        " inner join fetch ec.revision as r " +

Answer 4

与 OP 的特定查询无关，但对我来说，相同的查询指定了连接提取，但由于嵌套关系的JOIN FETCH语法不正确query specified join fetching, but the owner of the fetched association was not present in the select list ，它必须通过引用别名，而我直观地尝试通过完整路径引用它。

坏：（导致not present in the select list ）

SELECT * FROM TableA a
JOIN FETCH a.relationB
JOIN FETCH a.relationB.relationC

干得好！）

SELECT * FROM TableA a
JOIN FETCH a.relationB AS b
JOIN FETCH b.relationC

希望对某人有所帮助

Answer 5

此问题与 Spring Data 上的 N+1 问题有关，如果您打算使用 JpaSpecificationExecutor，您可以解决它，您可以将Page更改为Slice ，请查看此输入： 链接