Re: [eclipselink-users] loading collection problem

[Tom Ware <tom.ware@xxxxxxxxxx>]

Hi Leon,

  Can you post the generated SQL?

  Also, can you post your database and jdbc driver brand and version?

Thanks,
Tom

Leon Derks wrote:
> Hi Tom,
>
> When I run the SQL against my database it also doesn't return something. 
> So that is correct.
>
> I think I have to change my named query, but don't know how.
>
> I want to load a Lamp object with its collection of gears. If it has no 
> gears, then the collection has to be empty.
> The query I run now, return no Lamp at all.
>
> Leon
>
>
>
> Tom Ware wrote:
> > Hi Leon,
> >
> >   What SQL is your query producing?  If you run the SQL against your 
> > database, does it return a result?
> >
> >   To see the SQL, you can increase the logging level.  I suggest using 
> > the maximum logging level when debugging.  To do that, specify the 
> > persistence unit property in your persistence.xml
> >
> > <property name="eclipselink.logging.level" value="FINEST"/>
> >
> > -Tom
> >
> > Leon Derks wrote:
> > > Hello
> > >
> > > Thanks for the answer on my previous question. That works well!
> > >
> > > But now I have another problem.
> > > I want to load an object with a collection that may be empty.
> > >
> > > For example my Lamp object has a @ManyToMany relation with Gear.
> > >
> > > public class Lamp extends Product {
> > >
> > >    @ManyToMany
> > >    @JoinTable(name="PLI_LAMP_GEAR", joinColumns = 
> > > @JoinColumn(name="lamp_id", referencedColumnName = "ID"), 
> > > inverseJoinColumns = @JoinColumn(name="gear_id", referencedColumnName 
> > > = "ID"))
> > >    private List<Gear> gears = new ArrayList<Gear>()
> > >
> > > }
> > >
> > > public class Gear extends Product {
> > > }
> > >
> > > In my situation, the Lamp has no Gears, so the join table is empty 
> > > for this lamp.
> > >
> > > But when I try to load the Lamp it returns nothing. I want it to 
> > > return a Lamp (with name, description etc) and an empty collection of 
> > > Gears.
> > >
> > > This is my named query: "select l from Lamp l left join fetch l.gears 
> > > where l.id = :lampId"
> > >
> > > I tried several queries, but always get the message: 
> > > "javax.persistence.NoResultException: getSingleResult() did not 
> > > retrieve any entities."
> > >
> > > Am I doing something wrong?
> > >
> > > greetings,
> > > Leon
> > >
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