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k reid edited comment on HHH-6911 at 3/3/12 5:23 PM:
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Hmmm...guess I didn't search the forums well enough before opening a ticket for this
same issue. Hibernate supports this functionality using the xml descriptor but not using
annotations. Please review HHH-7144 and mark as duplicate if necessary.
Thanks.
was (Author: kor):
Hmmm...guess I didn't search the forums well enough before opening HHH-7144 for
this same issue. Please review it and mark as duplicate if necessary.
Thanks.
Write DiscriminatorValue to DiscriminatorColumn when combined with
InheritanceType#JOINED
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Key: HHH-6911
URL:
https://hibernate.onjira.com/browse/HHH-6911
Project: Hibernate ORM
Issue Type: Improvement
Components: annotations, metamodel
Reporter: Steve Ebersole
Priority: Minor
Labels: jpa2
The JPA spec states that {{DiscriminatorColumn}} can be used in conjunction with JOINED
inheritence. The only section that seems to deal with this combination is _11.1.10
DiscriminatorColumn Annotation_ where it says
{quote}
For the SINGLE_TABLE mapping strategy, and typically also for the JOINED strategy, the
persistence
provider will use a type discriminator column. The DiscriminatorColumn annotation is used
to
define the discriminator column for the SINGLE_TABLE and JOINED inheritance mapping
strategies.
{quote}
Apparently this is meant to imply that even if providers do not need/use the
discriminator for concrete class resolution (reading) they are still expected to write it
out to the database. Dunno, thats just what we have been told :)
Anyway, like I said, Hibernate itself does not need the discriminator column/value to
interpret the concrete classes. However, in the interest of portability we certainly
*could* write it out.
Longer term we could *possibly* even use the DiscriminatorColumn/DiscriminatorValue (if
present) instead of the SQL CASE statement thing we do now.
See HHH-4358 for the origins of this request...
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