objectbridge-developers

[OJB-developers] OQL bug

[Georg S. <ge...@me...>]

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

Re: [OJB-developers] OQL bug

[Georg S. <ge...@me...>]

Hi,

I thought a little bit about my last posting and of course the thing I did
was quite stupid since interfaces can not have fields. The query would
have to be
select allX from X where sequence.getSomeField() = $1

I do not know if this is correct OQL and even then it would be a
performance problem because the query engine would have to load each
object to invoke the method.

Anyway let me explain why I even got to that problem.
I actually wanted to do something like this:
select allX from X where sequence= $1

sequence is a reference field that holds an interface of type Sequence.

Please correct me if this is not possible in OQL, but I thought that I
could pass in an object when binding. My problem was that I passed in an
object which is loaded with dynamic proxy turned on. The query engine than
threw an error that it did not know a class $Proxy2. Somehow the engine
should substitute the actual interface or object for the proxy.

regards

Georg

On Fri, 8 Mar 2002, 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
>
>
> _______________________________________________
> Objectbridge-developers mailing list
> Obj...@li...
> https://lists.sourceforge.net/lists/listinfo/objectbridge-developers
>

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
> 
> 
> _______________________________________________
> Objectbridge-developers mailing list
> Obj...@li...
> https://lists.sourceforge.net/lists/listinfo/objectbridge-developers
> 
> 
> 
> 

[OJB-developers] Cache of Collections

[John W. <hw...@re...>]

I am wondering about how JOB handles the cache of collections?
Say, A has many B,
first I get A, it contains a collection of B, and the object A is put into
the cache
then Another user has added an object B, this time the object A's B
collection should contain the new B,
Can JOB handles that? Or at least it should invalidate the object A or A's B
collection.

BTW, does client/server model work for the current version? (0.7.343). And
it support distrubuted cache of objects?

Thanks a lot,
John W
----- Original Message -----
From: "Thomas Mahler" <tho...@ho...>
To: "Georg Schneider" <ge...@me...>
Cc: <obj...@li...>
Sent: Friday, March 08, 2002 10:59 AM
Subject: Re: [OJB-developers] OQL bug


> 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:6
6)
> >         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(PersistenceBr
okerImpl.java:1181)
> >         at
> >
ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery(PersistenceBr
okerImpl.java:901)
> >         at
> >
ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery(PersistenceBr
okerImpl.java:986)
> >         at
> >
ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery(PersistenceBr
okerImpl.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
> >
> >
> > _______________________________________________
> > Objectbridge-developers mailing list
> > Obj...@li...
> > https://lists.sourceforge.net/lists/listinfo/objectbridge-developers
> >
> >
> >
> >
>
>
>
>
> _______________________________________________
> Objectbridge-developers mailing list
> Obj...@li...
> https://lists.sourceforge.net/lists/listinfo/objectbridge-developers