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Posted to users@openjpa.apache.org by Chris Wolf <cw...@gmail.com> on 2013/04/11 22:24:18 UTC

What is the type parameter, 'X' for?

... in this interface?

public interface OpenJPAQuery<X> extends TypedQuery<X>

(an example would be good also)

Thanks,

Chris

Re: What is the type parameter, 'X' for?

Posted by Chris Wolf <cw...@gmail.com>.

Thanks, Pawel,

Yes, I normally try to stick with just javax.persistence API, but I wanted
to force fetching entire object graph and I thought eager fetching would do
that, as shown here:

http://openjpa.apache.org/builds/1.0.3/apache-openjpa-1.0.3/docs/manual/ref_guide_perfpack_eager.html

Example 5.23, but it didn't work...  (I still had to iterate over
relationship Lists to provoke fetching of related entities)

Thanks,

   -Chris




On Thu, Apr 11, 2013 at 4:38 PM, Pawel Veselov <pa...@gmail.com>wrote:

> On Thu, Apr 11, 2013 at 1:24 PM, Chris Wolf <cw...@gmail.com> wrote:
>
> > ... in this interface?
> >
> > public interface OpenJPAQuery<X> extends TypedQuery<X>
> >
> > (an example would be good also)
> >
>
> X is the class of the objects that the query is supposed to return.
>
>     TypedQuery<EAgent> agents =
>             em.createNamedQuery(EAgent.GET_ALL, EAgent.class);
>     for (EAgent agent : agents.getResultList()) {
>       // have fun
>     }
>
> (sorry, I don't use OpenJPA classes directly)
>
>
> >
> > Thanks,
> >
> > Chris
> >
>

Re: What is the type parameter, 'X' for?

Posted by Pawel Veselov <pa...@gmail.com>.

On Thu, Apr 11, 2013 at 1:24 PM, Chris Wolf <cw...@gmail.com> wrote:

> ... in this interface?
>
> public interface OpenJPAQuery<X> extends TypedQuery<X>
>
> (an example would be good also)
>

X is the class of the objects that the query is supposed to return.

    TypedQuery<EAgent> agents =
            em.createNamedQuery(EAgent.GET_ALL, EAgent.class);
    for (EAgent agent : agents.getResultList()) {
      // have fun
    }

(sorry, I don't use OpenJPA classes directly)


>
> Thanks,
>
> Chris
>

Re: What is the type parameter, 'X' for?

Posted by Rick Curtis <cu...@gmail.com>.

<X> is the query result type.

TypedQuery<Customer> q = em.createQuery("Select c FROM Customer c" ,
Customer.class);

Thanks,
Rick


On Thu, Apr 11, 2013 at 3:24 PM, Chris Wolf <cw...@gmail.com> wrote:

> ... in this interface?
>
> public interface OpenJPAQuery<X> extends TypedQuery<X>
>
> (an example would be good also)
>
> Thanks,
>
> Chris
>



-- 
*Rick Curtis*