AW: [eclipselink-users] questiona about JPQL and Collections

[<Daniel.Stucky@xxxxxxxxxxx>]

Hi Tom,

thanks for your help, in general it works as described by you.

However, I forgot to include the following member of RecordDao in the sample code:
  @Column(name = "RECORD")
  private byte[] _serializedRecord;

The generated SQL query contains DISTINCT, which is not usable with queries containing BLOBs.
Any suggestions how to handle this ?


Bye,
Daniel

> -----Ursprüngliche Nachricht-----
> Von: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-
> bounces@xxxxxxxxxxx] Im Auftrag von Tom Ware
> Gesendet: Mittwoch, 28. Januar 2009 21:12
> An: EclipseLink User Discussions
> Betreff: Re: [eclipselink-users] questiona about JPQL and Collections
> 
> Hi Daniel,
> 
>    Because BasicCollection is not a part of the JPA specification yet,
> JPQL
> cannot currently query across BasicCollections.  (That behavior is
> expected in
> the upcoming JPA 2.0 specification)
> 
>    To access a BasicCollection in a query, you will have to use
> EclipseLink's
> criteria API instead.
> 
>    Your code will look something like this:
> 
> ReadAllQuery query = new ReadAllQuery(RecordDAO.class);
> ExpressionBuilder record = new ExpressionBuilder();
> Expression attributes = record.anyOfAttributes("attributes");
> Expresion criteria =
> attributes.get("_name").equal(record.getParameter("name"));
> criteria =
> criteria.and(attributes.anyOf("_values").equal(record.getParameter("val
> ue")))
> query.setSelectionCriteria(criteria);
> 
> This query can be added as a named query through a SessionCustomizer by
> calling
> the addQuery(name, query) method.
> 
>    That is the basics of how it should look.  With a little massaging
> of the
> code, it should be possible to use this query just like any other named
> query in
> JPA.
> 
> BTW: Here is the Customizer doc:
> 
> http://wiki.eclipse.org/Using_EclipseLink_JPA_Extensions_%28ELUG%29#Usi
> ng_EclipseLink_JPA_Extensions_for_Customization_and_Optimization
> 
> -Tom
> 
> 
> 
> 
> Daniel.Stucky@xxxxxxxxxxx wrote:
> > Hi all,
> >
> > given the following Entities, how can I express a named query that
> > selects all Records where AttributeDao._name = "X" and
> > AttributeDao._values.contains("Y")
> >
> >
> > @Entity
> > @Table(name = "RECORDS")
> > public class RecordDao implements Serializable {
> >
> >   @Id
> >   @Column(name = "ID")
> >   private String _idString;
> >
> >   @Column(name = "SOURCE")
> >   private String _source;
> > ...
> > }
> >
> > @Entity
> > @Table(name = "ATTRIBUTES")
> > public class AttributeDao {
> >
> >   @Id
> >   @GeneratedValue(strategy=GenerationType.AUTO)
> >   @Column(name = "ATT_ID")
> >   private String _id;
> >
> >   @Column(name = "ATT_NAME")
> >   private String _name;
> >
> >   @BasicCollection (
> >     fetch=FetchType.EAGER,
> >     valueColumn=@Column(name="ATT_VALUE"))
> >     @CollectionTable (
> >         name="ATTRIBUTE_VALUES",
> >         primaryKeyJoinColumns=
> >         {@PrimaryKeyJoinColumn(name="ATT_ID",
> > referencedColumnName="ATT_ID")}
> >     )
> >   private List<String> _values;
> > ...
> > }
> >
> >
> >
> > I tried something like this
> >
> > @NamedQueries({
> >     @NamedQuery(name="RecordDao.findByAttribute",
> >       query="SELECT DISTINCT r FROM RecordDao r JOIN r._attributes a
> > JOIN a._values v WHERE a._name = :name AND v._values = :value")
> >
> > })
> >
> >
> > but during EntityManager creation I get the following error:
> >
> > Exception [EclipseLink-8030] (Eclipse Persistence Services - 1.0.2
> > (Build 20081024)): org.eclipse.persistence.exceptions.JPQLException
> > Exception Description: Error compiling the query
> > [RecordDao.findByAttribute: SELECT DISTINCT r FROM RecordDao r JOIN
> > r._attributes a JOIN a._values v WHERE a._name = :name AND v._values
> =
> > :value], line 1, column 63: unknown state or association field
> [_values]
> > of class [org.eclipse.smila.datamodel.persistence.AttributeDao].
> >
> >
> > I expect the syntax for "AND v._values = :value" to be not valid, but
> I
> > wonder why it complains about JOIN a._values v.
> > Anyone any ideas/suggestions ?
> >
> >
> > Bye,
> > Daniel
> > _______________________________________________
> > eclipselink-users mailing list
> > eclipselink-users@xxxxxxxxxxx
> > https://dev.eclipse.org/mailman/listinfo/eclipselink-users
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