AW: [eclipselink-users] Beginner question concerning Collectionsand Maps

[<Daniel.Stucky@xxxxxxxxxxx>]

Hi Tom,

thanks for your answer. With the extensions I was easily able to annotate List<String> and Map<String, String>.

Is it also possible to use Map<String, byte[]> ?

I tried it out and got an Internal Exception: java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.GenericArrayTypeImpl

I know from the documentation that it's possible to use byte[] as fields, like
	@Lob
	@Basic(fetch=LAZY)
	@Column(name="EMP_PIC", columnDefinition="BLOB NOT NULL")
	protected byte[] pic;

I also tried to somehow combine the annotations for the byte[] with the @BasicMap extension, but without any success so far.

Bye,
Daniel


> -----Ursprüngliche Nachricht-----
> Von: eclipselink-users-bounces@xxxxxxxxxxx [mailto:eclipselink-users-
> bounces@xxxxxxxxxxx] Im Auftrag von Tom Ware
> Gesendet: Donnerstag, 22. Januar 2009 15:03
> An: EclipseLink User Discussions
> Betreff: Re: [eclipselink-users] Beginner question concerning
> Collectionsand Maps in JPA
> 
> Hi Daniel,
> 
>    The problem you are seeing is because Lists and Maps of primitives
> are
> covered by an EclipseLink extension to JPA rather than the
> specification itself.
>   Take a look at the following documentation for information on how to
> use those
> extensions:
> 
> http://wiki.eclipse.org/Using_EclipseLink_JPA_Extensions_%28ELUG%29#How
> _to_Use_the_.40BasicCollection_Annotation
> http://wiki.eclipse.org/Using_EclipseLink_JPA_Extensions_%28ELUG%29#How
> _to_Use_the_.40BasicMap_Annotation
> 
>    If you are concerned about using JPA in a portable manner, it is my
> understanding that the upcoming JPA 2.0 specification will cover those
> scenarios.  EclipseLink is the reference implementation for that
> specification
> and will ship an implementation with the specification.
> 
> -Tom
> 
> Daniel.Stucky@xxxxxxxxxxx wrote:
> > Hi all,
> >
> > I'm from the SMILA project and new to eclipseLink. Some of the 3rd
> party
> > components we use in SMILA already make use of eclipseLink, so we are
> > thinking about using eclipseLink (JPA) for persisting our own data as
> > well.
> >
> > Our datamodel, being recursive, is a bit complex. Here is an overview
> of
> > the classes containing only the member variables that need to be
> > persisted.
> >
> > public class RecordImpl implements Record, Serializable {
> >   private IdImpl _id;
> >   private MObject _metadata = new MObjectImpl();
> >   private final Map<String, byte[]> _attachments = new
> > LinkedHashMap<String, byte[]>();
> >   ...
> > }
> >
> >
> > public class IdImpl implements Id {
> >   private String _source;
> >   private Key _key;
> >   private List<KeyImpl> _elementKeys;
> >   private List<String> _fragmentNames;
> >   ...
> > }
> >
> >
> > public class KeyImpl implements Key {
> >   private String _simpleKey;
> >   private String _simpleKeyName;
> >   private Map<String, String> _compositeKey;
> >   ...
> > }
> >
> >
> > public class MObjectImpl extends AttributeValueImpl implements
> MObject {
> >   private final Map<String, AttributeImpl> _attributes = new
> > LinkedHashMap<String, AttributeImpl>();
> >   ...
> > }
> >
> >
> > public class AttributeImpl extends AnnotatableImpl implements
> Attribute
> > {
> >  private String _name;
> >   private List<LiteralImpl> _literalValues;
> >   private List<MObjectImpl> _metadataObjects;
> >   ...
> > }
> >
> >
> > public abstract class AttributeValueImpl extends AnnotatableImpl
> > implements AttributeValue {
> >   private String _semanticType;
> >   ...
> > }
> >
> >
> > public abstract class AnnotatableImpl implements Annotatable,
> > Serializable {
> >   private MultiValueMap _annotationMap;
> >   ...
> > }
> >
> >
> > public class LiteralImpl extends AttributeValueImpl implements
> Literal {
> >   private Object _value;
> >   private DataType _dataType;
> >   ...
> > }
> >
> >
> > To get started I annotated all members with @Transient and tried to
> > replace every one step by step with "correct annotations".
> >
> > Currently I'm running into problems finding the right annotations for
> > the Collections and Maps. I read a lot about it in your documentation
> > (thumbs up, it's really extensive) but I'm not able to understand the
> > meaning of the annotations and so can't find answers to my problems.
> >
> > E.g.
> > - for Map<String, String> the follwoing error message occurs:
> > Exception Description: [class
> > org.eclipse.smila.datamodel.id.impl.KeyImpl] uses a non-entity [class
> > java.lang.String] as target entity in the relationship attribute
> > [private java.util.Map
> > org.eclipse.smila.datamodel.id.impl.KeyImpl._compositeKey].
> > - for List<String> _fragmentNames the follwoing error message occurs:
> > Exception Description: [class
> > org.eclipse.smila.datamodel.id.impl.IdImpl] uses a non-entity [class
> > java.lang.String] as target entity in the relationship attribute
> > [private org.eclipse.smila.datamodel.id.impl.IdImpl._fragmentNames].
> >
> >
> >
> > It would be great if I could get some feedback about
> > - if it's generally possible to persist our datamodel with
> eclipseLink
> > JPA or if there are java constructs that are simply not supported by
> > JPA/eclipseLink
> > - how to annotate collections and maps
> > - how to use non entity classes in collections/maps
> >
> > Thanks a lot !
> >
> > Bye,
> > Daniel
> > _______________________________________________
> > eclipselink-users mailing list
> > eclipselink-users@xxxxxxxxxxx
> > https://dev.eclipse.org/mailman/listinfo/eclipselink-users
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