Re: [eclipselink-users] Looking for hints to map inheritance relationshi

[Tom Ware <tom.ware@xxxxxxxxxx>]

Hi Phillip,

  Can you please post the following:

- examples of how the category fields are mapped in both Product and Automobile
- a code snippet the shows what you are doing
- logging of the SQL produced and the full exception trace (for logging, use 
persistence unit property eclipselink.logging.level=FINEST)

-Tom

Phillip Ross wrote:
> Hi all, I'm having a problem with mapping inheritance and not sure if
> things are acting correctly or not.  Was hoping for some hints.
>
> The scenario I'm working with is that I have two related entity
> superclasses mapped with an inheritance strategy or JOINED, and there
> is a ManyToOne relationship between the two.  The subclass entities
> subclass the superclasses and override the relationship (or at least
> this is what is intended).  I had first assumed that when the tables
> were created, a field would be created in both the parents table and
> child table... but it appears that it was only created in the parent
> table.  I figured that this was OK since there would be records in the
> parent tables that would map related subclass instances, but when I
> attempt to persist the subclass with the ManyToOne member attribute...
> an exception is thrown caused by a not-null constraint violation
> corresponding to the parent table's FK field.  As an experiment, I
> changed the child class to populate the related property field in both
> the superclass and itself, but I'm assuming this won't really work out
> in the future as fetching the correct records may not work either.
>
> To put this in more concrete terms... say I have Product and
> ProductCategory as superclasses.  Product has a property called
> category which holds a ProductCategory instance.  Automobile
> subclasses Product and AutomobileCategory subclasses ProductCategory.
> The Automobile class defined a property named category and is defined
> to be AutomobileCategory.  Since persisting an Automobile and an
> AutomobileCategory would create records in all four tables... shouldnt
> eclipselink know that the category field in the Product table relating
> to ProductCategory be used to map the Automobile instances to the
> AutomobileCategory instances?
>
> I'm hoping someone knoww if I'm trying to map a scenario that's not
> supported or if there is a trick to doing this?  Perhaps an
> eclipselink specific trick that goes beyond the JPA spec?  If it is
> supported and sounds like a bug... I have a test case to submit :)
>
> Thanks!
> - Phillip
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