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我在尝试让 Envers 执行我需要的查询时遇到了很大的问题。如果有人可以让我知道这是否可以从 Envers 内部实现，或者我是否需要直接执行 SQL，那将是一个巨大的帮助！

这是问题所在。我有一个虚构的“项目”实体——任何实体类都可以——已经过审计。我正在尝试通过 AuditReader 查询获取每个项目实体的最新版本。

当我这样做时（代码的其他部分无关紧要）：

AggregatedAuditExpression maxExpression = AuditEntity.revisionNumber().maximize();
maxExpression.add(AuditEntity.id().eq("12345"));
query.add(maxExpression);

并打开 SQL 输出，我看到正在生成这个查询：

Hibernate: select project_a0_.id as id6_0_, project_a0_.REV as REV6_0_, auditrevis1_.id as id0_1_,
project_a0_.REVTYPE as REVTYPE6_0_, project_a0_.description as descript4_6_0_, 
auditrevis1_.timestamp     as timestamp0_1_, auditrevis1_.username as username0_1_ 
from MYSCHEMA.project_AUD project_a0_ cross join MYSCHEMA.REVINFO auditrevis1_ 
where project_a0_.REV=

(select max(project_a2_.REV) from MYSCHEMA.project_AUD project_a2_ 
               where project_a2_.id=?) 

and project_a0_.REV=auditrevis1_.id order by project_a0_.REV asc

注意“选择最大值”部分。这几乎正​​是我所需要的。只是 where 子句是错误的，我需要它说： where project_a2_.id=project_a0_.id

我手动编辑它，运行它，它工作得很好。现在它看起来像 IdMapper 类中的“addIdsEqualToQuery”方法让我做我想做的事。因此，如果我将 AuditEntity.id().eq("12345") 更改为：

maxExpression.add(new IdentifierIdsEqAuditExpression());

其中 IdentifierIdsEqAuditExpression 等于：

    class IdentifierIdsEqAuditExpression implements AuditCriterion {    
        @Override
        public void addToQuery(AuditConfiguration auditCfg, String entityName, QueryBuilder qb, Parameters parameters) {
            auditCfg.getEntCfg().get(entityName).getIdMapper()
                    .addIdsEqualToQuery(parameters, null, auditCfg.getAuditEntCfg().getOriginalIdPropName());
        }    
    }

它应该很接近 - 它是。我得到：

无效路径：'originalId.id' [select e__, r from com.mycompany.Project_AUD e_ , com.mycompany.audit.AuditRevisionEntity r where id = originalId.id and e _.originalId.REV.id = (select max(_e0 .originalId.REV.id) 来自 com.mycompany.Project_AUD e0 其中 id = originalId.id) 和 e _.originalId.REV.id = r.id order by e__.originalId.REV.id asc]

The problem is I can't get it to generate what I need and even if the prefix was changed from "originalId" to the correct one, why does envers start putting that all over the place, rather than in the single location?

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1 回答 1

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I'm afraid this is not currently possible with Envers. You would need to add something like parentIdEqual() to maxExpression, but there's no combinator like that.

Please open a feature request: https://hibernate.onjira.com/secure/Dashboard.jspa

As for the originalId, Envers entities have a composite id of the revision number and the original id (which is kept in the originalId sub-property).

于 2012-11-24T20:34:56.943 回答