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From Fay Wang <fyw...@yahoo.com>
Subject Re: Can't query against a MappedSuperclass
Date Tue, 21 Apr 2009 16:32:04 GMT

Just found that in JPA 2.0 Proposed Final Draft (March 13, 2009): 

Spec 2.11.2:
A mapped superclass, unlike an entity, is not queryable and cannot be passed as an argument
to EntityManager or Query operations.


--- On Tue, 4/21/09, Jeremy Bauer <techhusky@gmail.com> wrote:

> From: Jeremy Bauer <techhusky@gmail.com>
> Subject: Re: Can't query against a MappedSuperclass
> To: users@openjpa.apache.org
> Date: Tuesday, April 21, 2009, 8:52 AM
> Hi Jim,
> 
> It looks like there are inconsistencies in the manual and
> provider.  I was
> able use the em.find() operation with a mapped superclass,
> but could not run
> a JPQL query which used one.  To perform the find
> operation, OpenJPA queried
> known entity subclasses of the mapped superclass until it
> found one that
> matched the specified ID.  I tried using mapped
> superclasses with the base
> 1.0 release to make sure this capability hadn't regressed
> and 1.0 behaved
> the same. So, it doesn't look like this ever worked with
> JPQL.
> 
> Have you taken a look at using entity enheritance and the
> various entity
> inheritance strategies?  The TABLE_PER_CLASS strategy
> may map fairly well to
> a domain model that currently uses mapped superclass over
> multiple disparate
> entities.  It provides query capabilities over the
> superclass entity type.
> 
> I've opened JIRA OPENJPA-1043[1] for this issue. 
> Minimally, the docs should
> be updated to reflect that mapped superclasses are only
> supported on a find
> until such a time they can be supported in a query.
> 
> -Jeremy
> 
> [1] https://issues.apache.org/jira/browse/OPENJPA-1043
> 
> On Mon, Apr 20, 2009 at 4:33 PM, Fay Wang <fyw300@yahoo.com>
> wrote:
> 
> >
> > Hi,
> > According to openjpa manual:
> >
> > "Unlike true entities, you cannot query a mapped
> superclass"
> >
> >
> > http://openjpa.apache.org/builds/latest/docs/manual/manual.html#jpa_overview_meta_embeddablesuper
> >
> >
> >
> > --- On Mon, 4/20/09, jim weaver <jeweaver@us.ibm.com>
> wrote:
> >
> > > From: jim weaver <jeweaver@us.ibm.com>
> > > Subject: Can't query against a MappedSuperclass
> > > To: users@openjpa.apache.org
> > > Date: Monday, April 20, 2009, 12:38 PM
> > >
> > > I have the following:
> > >
> > > @MappedSuperclass class A { }
> > > @Entity class B extends A { }
> > > @Entity class C extends A { }
> > >
> > > and I try to do this type of query: SELECT a FROM
> A a
> > >
> > > I receive error message "An error occurred while
> parsing
> > > the query filter
> > > "SELECT a FROM A a".  Error
> > > message:   The name "A" is not a
> recognized
> > > entity or identifier.  Perhaps you meant B,
> which is a
> > > close match.  Known
> > > entity names: [B, C]"
> > >
> > > A is defined in my persistence.xml and my tables
> do have
> > > the inherited
> > > fields from it so I'm pretty sure jpa is
> recognizing it.
> > >
> > > The OpenJPA doc says that the query is
> supported.....this
> > > is from the 1.2.0
> > > doc:
> > >
> > > Note
> > > OpenJPA allows you to query on mapped
> superclasses. A query
> > > on a mapped
> > > superclass will return all matching subclass
> instances.
> > >
> > >
> > > --
> > > View this message in context:
> > http://n2.nabble.com/Can%27t-query-against-a-MappedSuperclass-tp2665700p2665700.html
> > > Sent from the OpenJPA Users mailing list archive
> at
> > > Nabble.com.
> > >
> > >
> >
> >
> >
> >
> 


      

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