[hibernate-issues] [Hibernate-JIRA] Commented: (ANN-140) Discriminator column not supported with JOINED strategy

[Ortwin Glück (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/ANN-140?page=comments#action_24049 ] 

Ortwin Glück commented on ANN-140:
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A discriminator column can also be used to choose the right subclass for a lazy proxy. Now in a lazy OneToOne the proxy is always the topmost class, which is bad, because there is no way of telling the real class behind the proxy! I strongly suggest to revisit this issue and use an optional discriminator column as a hint.

See http://forum.hibernate.org/viewtopic.php?p=2319629#2319629 for an example.

> Discriminator column not supported with JOINED strategy
> -------------------------------------------------------
>
>          Key: ANN-140
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/ANN-140
>      Project: Hibernate Annotations
>         Type: Bug

>     Versions: 3.1beta6
>  Environment: Hibernate 3.1rc2, Hibernate Annotations 3.1b6
>     Reporter: Steven Grimm

>
>
> Section 9.1.27 of the EJB3 persistence public draft says, "The DiscriminatorColumn annotation is used to define the discriminator column for SINGLE_TABLE and JOINED mapping strategies." But Hibernate ignores the DiscriminatorColumn annotation when the mapping strategy is JOINED; when a JOINED entity is persisted, its discriminator column is not included in the SQL "insert" statement, resulting in a not-null constraint violation if the discriminator column is marked NOT NULL in the database.
> The JOINED strategy with discriminators is pretty ubiquitous in EJB3 sample code and tutorials out on the net, so lots of people are likely to run into this as they try out EJB3 for the first time. A few examples:
> http://www.oracle.com/technology/tech/java/oc4j/ejb3/howtos-ejb3/howtoejb30inheritance/doc/how-to-ejb30-inheritance.html
> http://www.solarmetric.com/Software/Documentation/4.0.0EA/docs/full/html/ejb3_overview_mapping_discrim.html
> http://www.caucho.com/resin-3.0/amber/tutorial/cmp-inherit/index.xtp

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