[hibernate-issues] [Hibernate-JIRA] Created: (HHH-3528) FETCH JOIN query doesn't work in a StatelessSession

[Oscar Pearce (JIRA)]

FETCH JOIN query doesn't work in a StatelessSession
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                 Key: HHH-3528
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3528
             Project: Hibernate Core
          Issue Type: Bug
          Components: core
    Affects Versions: 3.3.1, 3.2.6
         Environment: Hibernate core 3.3.1 and 3.2.6, HSQLDB 1.8.0 and PostgreSQL 8.1
            Reporter: Oscar Pearce
         Attachments: slsession.zip, StatelessSessionImpl.patch

A query with an explicit JOIN FETCH, such as the following:

from DomainObject obj join fetch obj.a

fails when run in a StatelessSession, giving the following exception:

org.hibernate.SessionException: proxies cannot be fetched by a stateless session
	at org.hibernate.impl.StatelessSessionImpl.immediateLoad(StatelessSessionImpl.java:243)
	at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:95)
	at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:140)
	at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:190)

The attached zip file contains a small project (buildable with maven) that demonstrates the problem.  Applying the patch to StatelessSessionImpl fixes it.

The cause of the problem is with the internalLoad method of StatelessSessionImpl.  The method currently first tries to generate a proxy and, only if no proxy is available, then it uses the data that it loaded as part of the query.  The patch changes it to use any loaded data from the query in preference to creating a proxy.  (I suspect that the check for eager should be omitted, and that an exception should be thrown if getEntity fails and no proxy can be created, but I don't know the code well enough to be sure of that.)

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