Re: [eclipselink-users] Embeddables and inheritance

["Guy Pelletier" <guy.pelletier@xxxxxxxxxx>]

Hi Laird,

I believe the confusion or interpretation may of stemed from the definition 
of the @Inheritance and @MappedSuperclass

"
The Inheritance annotation defines the inheritance strategy to be used for 
an entity class hierarchy.
It is specified on the entity class that is the root of the entity class 
hierarchy.

The MappedSuperclass annotation designates a class whose mapping information 
is applied to the
entities that inherit from it. A mapped superclass has no separate table 
defined for it.
"

However, internally Eclipselink can already support those configurations but 
you have to set them manually using a descriptor customizer. Please enter a 
bug to have this corrected by the metadata processing.

Cheers,
Guy

----- Original Message ----- 
From: Laird Nelson
To: EclipseLink User Discussions
Sent: Monday, August 03, 2009 11:24 AM
Subject: [eclipselink-users] Embeddables and inheritance


The specification says, with regard to @Embeddable classes:

Embeddable classes must adhere to the requirements specified in Section 2.1 
for entities with the exception
that embeddable classes are not annotated as Entity.


Section 2.1.9, a sub-section of Section 2.1, and therefore included by it, 
includes the stanza:

An entity may inherit from another entity class.


That tells me that @Embeddables should be allowed to inherit from one 
another in exactly the same way that entities are allowed to inherit from 
one another.

I have one @Embeddable class (GeneralLedgerAccountIdentifier) that inherits 
from another (GeneralLedgerAccountType), and, at the moment, adds no 
additional state information (so no additional persistent fields, although I 
plan to add some later).  I have another class that uses this @Embeddable as 
its primary key, via the @EmbeddedId annotation.

EclipseLink (1.1.2-SNAPSHOT) bombs out and says:

Exception Description: Entity [class ljn.GeneralLedgerAccount] uses [class 
ljn.GeneralLedgerAccountIdentifier] as embedded id class whose access-type 
has been determined as [FIELD]. But [class 
ljn.GeneralLedgerAccountIdentifier] does not define any [FIELD]. It is 
likely that you have not provided sufficient metadata in your id class 
[class ljn.GeneralLedgerAccountIdentifier].


Neither OpenJPA nor Hibernate have a problem with this particular 
construction and work properly in my opinion.

Should I file a bug, or is there a nuance in the specification I am not 
aware of that governs this case?

Thanks,
Laird




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