[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2831) Native SQL queries with addJoin or <return-join/> return object arrays instead of single Entities

[Jeremy Grodberg (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2831?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_28078 ] 

Jeremy Grodberg commented on HHH-2831:
--------------------------------------

Max Rydahl Andersen wrote : this is just how it was done initially....addJoin both eager fetch and return the result. 

Max, I'm not sure what you are saying.   Are you saying it was intended for addJoin to behave like addEntity for associated objects or rather that it wasn't fully thought out?

How is addJoin (supposed to be) different than addEntity?  It seem like now all it does is let you specify the entity class by referring to a property rather than naming the class explicitly, which is not nearly as useful as being able to turn on or off eager fetching in my externalized named SQL queries without having to dive into the Java code to change the handling of the list that the query returns. (In my case I had to turn it on to avoid a massive N+1 selects problem when an association was added to the root entity.)

In HQL queries I can eagerly fetch an association by using LEFT JOIN FETCH and the associated objects are not returned directly in the query results; the result is a list of root entities.  It sure looks from the documentation like addJoin was meant to be analogous for SQL queries and it sure would be helpful to have an analog of LEFT JOIN FETCH for SQL queries.

So, if you are saying that the behavior I see is the design intention for addJoin and <return-join/> then please change the "component" of this issue from query-sql to documentation and clarify the documentation of these features to indicate that eager fetching this way WILL return the associated objects directly as well as in the properties of the root entity and I will file a separate enhancement request to provide for SQL queries an analog of LEFT JOIN FETCH.

However, I'd really prefer it if you did not return the associated entities fetched with addJoin directly, since I can already get the entities returned if I want that by using addEntity.

> Native SQL queries with addJoin or <return-join/> return object arrays instead of single Entities
> -------------------------------------------------------------------------------------------------
>
>                 Key: HHH-2831
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2831
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: query-sql
>    Affects Versions: 3.2.4, 3.2.5
>         Environment: Hibernate 3.2.4.ga and 3.2.5.ga with hsqldb on Win XP
>            Reporter: Jeremy Grodberg
>         Attachments: NativeSQLQueriesTest.patch
>
>
> Although the documentation is not crystal clear, I read it to say that using addJoin should eagerly fetch an associated object but should NOT return it as a separate value.  In section 16.1.3. "Handling associations and collections" of the online documentation it says: "It is possible to eagerly join in the Dog to avoid the possible extra roundtrip for initializing the proxy. This is done via the addJoin() method, which allows you to join in an association or collection."  This comes BEFORE the section on returning multiple entities, so I say the documentation at least implies it will only return a single entity at the top level.  Also, if the intention is to return multiple entities, addEntity() works fine for that, so what then would be the difference of addJoin()?  If I'm wrong about what addJoin() should do, please clarify that in the documentation and also clarify how, if it is possible, one could eagerly fetch the association without changing the return type of the qu
 ery.
> I have reproduced this problem in the Hibernate JUnit tests in 3.2.4.ga and 3.2.5.ga, specifically NativeSQLQueriesTest.testSQLQueryInterface().
> I'm attaching a patch to the Hibernate junit test org.hibernate.test.sql.hand.query.NativeSQLQueriesTest.java released in 3.2.5.ga that adds a test to ensure that a query with addJoin only returns a (list of) entities, not a list of Object arrays containing entities.  Currently, the assertion fails because instead of returning a list of Organizations we get a list of Object[3] = { Organization, Employment, Person }, which is exactly what we get when the addJoin()s are replaced with appropriate addEntity() calls.

-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: http://opensource.atlassian.com/projects/hibernate/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira