[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-5393) @MapKey with embeddable value

[Harald Wellmann (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-5393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=37854#action_37854 ] 

Harald Wellmann commented on HHH-5393:
--------------------------------------

Actually, this is not quite the same thing as HHH-5136 (or maybe I shouldn't have mixed two aspects in that earlier issue).

HHH-5136 was mainly about the fact that overriding the mapped table and column names only works when the mappings are specified by annotations and has no effect when using XML mappings instead.

Meanwhile, I've had some interesting feedback on this from Mike Keith (see the comments to my blog post cited above). As Mike points out, @MapKey was only intended by the spec for the case Map<Basic, Entity>, not for Map<Basic, Embeddable>. The correct annotation for embeddable values would be

@MapKeyColumn(name = "language", insertable = false, updatable = false)

But in this case, I get the following exception from Hibernate:

org.hibernate.MappingException: Repeated column in mapping for collection: MultilingualString.map column: language



> @MapKey with embeddable value
> -----------------------------
>
>                 Key: HHH-5393
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5393
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: annotations
>    Affects Versions: 3.5.3
>         Environment: Hibernate 3.5.3, PostgreSQL 8.4.3
>            Reporter: Harald Wellmann
>            Assignee: Gail Badner
>
> Map<Basic, Embeddable> does not work, when the map key is a persistent field of the value. The map key shall not be represented as a separate table column, this is why the example uses @MapKey and not @MapKeyColumn.
> Example:
> {code:java}
> @Embeddable
> public class LocalizedString {
>     private String language;
>     private String text;
> } 
>  
> @Entity
> public class MultilingualString {
>     @Id
>     private long id;
>     @ElementCollection(fetch=FetchType.EAGER)
>     @MapKey(name = "language")
>     @CollectionTable(schema = "jpa", name = "multilingual_string_map", 
>                      joinColumns = @JoinColumn(name = "string_id"))
>     private Map<String, LocalizedString> map = new HashMap<String, LocalizedString>();
> }
> {code}
> Hibernate appears to expect an Entity as map value: 
>  org.hibernate.AnnotationException: Associated class not found: LocalizedString
> Detailed discussion of this use case:
> http://hwellmann.blogspot.com/2010/07/jpa-20-mapping-map.html

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