Re: [OJB-developers] OQL bug

[Thomas M. <tho...@ho...>]

Hi Georg,

Oops this is a very tough problem. This will be quite difficult to fix.
The best thing would be to support usage of methods in OQL query like
"select x from X where getSequence().getSomeField() = $1"

This way we could avoid all the trouble caused by looking for persistent 
attributes in interface classdescriptors.

I'll put this on the todo list. But it will take some time to fix! (Any 
volunteers?)

thanks,

Thomas

Georg Schneider wrote:

> Hi,
> 
> when something similar as the following OQL-Query
> 
> select allX from X where sequence.somefield = $1 ....
> 
> where the sequence field is actually an interface I get a
> NullPointerException:
> 
> java.lang.NullPointerException
>         at
> ojb.broker.metadata.ClassDescriptor.getPkFields(ClassDescriptor.java:869)
>         at
> ojb.broker.accesslayer.SqlGenerator$JoinInfo.asSqlClause(SqlGenerator.java:66)
>         at
> ojb.broker.accesslayer.SqlGenerator.getJoinClause(SqlGenerator.java:914)
>         at
> ojb.broker.accesslayer.SqlGenerator.getPreparedSelectStatement(SqlGenerator.java:685)
>         at
> ojb.broker.accesslayer.JdbcAccess.executeQuery(JdbcAccess.java:186)
>         at ojb.broker.accesslayer.RsIterator.<init>(RsIterator.java:179)
>         at
> ojb.broker.singlevm.PersistenceBrokerImpl.getIteratorFromQuery(PersistenceBrokerImpl.java:1181)
>         at
> ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery(PersistenceBrokerImpl.java:901)
>         at
> ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery(PersistenceBrokerImpl.java:986)
>         at
> ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery(PersistenceBrokerImpl.java:958)
>         at ojb.odmg.oql.OQLQueryImpl.execute(OQLQueryImpl.java:229)
> 
> 
> I looked a little bit around and the problem seems to be in the inner
> class JoinInfo in SqlGenerator which tries to do the following
> 
>             refCld =
> aCld.getRepository().getDescriptorFor(anOrd.getItemClass());
> 
> 
> anOrd.getItemClass() of course is an interface which as a Descriptor
> doesn't have any fields. I suppose the interface would have to be
> substituted somehow by the actual classes implementing that interface and
> maybe this would mean having to do various actual SQL-Queries each with a
> concrete class and then somehow merging the result, or doing an
> (outer) join over all the concrete class tables involved and then somehow
> postprocessing the result again.
> 
> regards
> 
> Georg
> 
> 
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