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Posted to jdo-dev@db.apache.org by "Michael Bouschen (JIRA)" <ji...@apache.org> on 2011/05/19 21:06:47 UTC
[jira] [Commented] (JDO-652) Provision of a typesafe
refactor-friendly query capability for JDOQL
[ https://issues.apache.org/jira/browse/JDO-652?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13036377#comment-13036377 ]
Michael Bouschen commented on JDO-652:
--------------------------------------
I looked at the JDOQL "typesafe" query API.
The expression syntax is looking good, but I have some questions about the handling of query parameters and specifying the query result. My concern is that the typesafe query API is using a very different aproach compared to the regular JDO queries.
- Parameter handling:
The typesafe query API uses a method setParameter to set the parameter value, meaning the parameters values are part of the state of the TypesafeQuery instance. With JDO queries parameter values are passed as arguments to the Query.execute call and not stored in the Query state.
- Query result specification:
The typesafe query API used a special execute method executeResultList to specify the query result, e.g. tq.executeResultList(String.class, false, cand.lastname). At first glance this looks like an execute call taking parameter values, but it is not. The reason might be, that this aproach allows tempating on the query result. An alternative would be specifying the query result type as a tempate argument of the TypesafeQuery instance, in addition to the candidate class.
What do you think?
> Provision of a typesafe refactor-friendly query capability for JDOQL
> --------------------------------------------------------------------
>
> Key: JDO-652
> URL: https://issues.apache.org/jira/browse/JDO-652
> Project: JDO
> Issue Type: New Feature
> Components: api, specification, tck
> Reporter: Andy Jefferson
> Fix For: JDO 3 maintenance release 1
>
> Attachments: typesafe.patch, typesafe_manifest.patch
>
>
> There are various querying capabilities of this type around. JPA2 has its Criteria query API. Third party solutions like QueryDSL also exist, in its case providing a JDOQL implementation (as well as JPQL, and HQL). We should seriously consider introducing something along these lines in the JDO2.4 timeframe.
> There is a comparison of JPA Criteria with QueryDSL over at
> http://source.mysema.com/forum/mvnforum/viewthread_thread,49
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