[hibernate-issues] [Hibernate-JIRA] Resolved: (ANN-494) Determine Referenced Entity For Embeddable types from the parameterised type

[Paolo "Nusco" Perrotta (JIRA)]

     [ http://opensource.atlassian.com/projects/hibernate/browse/ANN-494?page=all ]
     
Paolo "Nusco" Perrotta resolved ANN-494:
----------------------------------------

    Resolution: Fixed

This was two separate problems with the reflection layer. The @Embedded problem was a bug in the propagation of type bindings. The @CollectionOfElements problem has to do with XClass identity. Both bugs were very subtle.

I think I'll give some thought to class identity and type bindings within the reflection layer, because we might have more corner cases with complicated structures involving generic types. Emmanuel, can you please review the new code? It's on the 3_2 branch.

Edward, I edited your test case a lot. Now it does a full persistence cycle instead of just configuration (I'm paranoid). I left your name in, of course.


> Determine Referenced Entity For Embeddable types from the parameterised type
> ----------------------------------------------------------------------------
>
>          Key: ANN-494
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/ANN-494
>      Project: Hibernate Annotations
>         Type: Improvement

>   Components: binder
>     Versions: 3.2.0.cr1
>     Reporter: Edward Costello
>     Assignee: Paolo "Nusco" Perrotta
>  Attachments: TestUnboundEntity-no-copyrite.java, TestUnboundEntity.java
>
>
> When a collection is mapped using @ManyToOne or @CollectionOfElements, the entity in the collection is derived from the parametrised type of the collection. e.g. there is no need to explicitly indicate the elements of the following collection are books.
> @ManyToOne
> Set<Book> books;
> It would be nice if the same kind of discovery could be applied to Embeddable types when contained in a CollectionOfElements. E.g. it would be nice if Hibernate could derive that the embedded Versioned references a Book in the example below
> @CollectionOfElements
> Set<Versioned<Book>>;
> @Embeddable
> class Versioned<T> {
>     T rightSide;
>     Date date;
> }
> Even if it wasn't derived, it would be good to be able to specify it. Currently the only way to make the above work is to create a subclass of Versioned that explicitly binds the type parameter to Book. Without this the below exception is thrown while building the session factory
> Exception in thread "main" java.lang.IllegalStateException: Property rightSide has an unbound type and no explicit target entity.
>    at org.hibernate.cfg.AnnotationBinder.addElementsOfAClass(AnnotationBinder.java:946)
>    at org.hibernate.cfg.AnnotationBinder.fillComponent(AnnotationBinder.java:1655)
>    at org.hibernate.cfg.annotations.CollectionBinder.bindManyToManySecondPass(CollectionBinder.java:1054)
>     at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:543)
>    at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:484)
>    at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:43)
>    at org.hibernate.cfg.annotations.CollectionBinder.bind(CollectionBinder.java:377)
>    at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1476)
>    at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:706)
>    at org.hibernate.cfg.AnnotationConfiguration.processArtifactsOfType(AnnotationConfiguration.java:452)
>    at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:268)
>    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1210)

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