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[TEXO] Mapped superclass in a containment relation [message #1621102]

Tue, 17 February 2015 17:19

Mr Cur

Messages: 35
Registered: September 2014

Member

Hi,

I have the following classes and relations:

A<*>-----------------(hasS)----B
^
|
----------------------
| | |
C D E

A decomposes into (many) B's, being C, D, and E's.
Therefore, C, D, and E are subclasses of B.

Since many instances of C, D, and E are generated in application, I want to have them in seperate tables. To do so, I defined an MAPPED SUPERCLASS annotation for B. Code generation goes fine.

If I however create an instane of A and C, and try to populatie de decomposition relation between A en C (via B) I get the following error:

(Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.ValidationException
Exception Description: [class A] uses a non-entity [class B] as target entity in the relationship attribute [field hasS].

If I ommit the MAPPED SUPERCLASS annotation everything is put in a table B (so C, D, and E) and everything works fine.

Thanks for your help.

Cur.

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Re: [TEXO] Mapped superclass in a containment relation [message #1621143 is a reply to message #1621102]

Tue, 17 February 2015 17:56

Martin Taal

Messages: 5468
Registered: July 2009

Senior Member

Hi Cur,
If B is mapped as a mapped super class, this means that C, D and E each will be stored in their own respective tables.
This has as a consequence that when loading an instance of A, that the ORM needs to read from three tables and then
somehow consolidate them for the association. The ORM probably does not do that and expects to work with one table for
one association.

You can try by using a join table for the association, this could work or not.. but is worth a try. (I am not sure).

If that doesn't work then I guess mapped super class wont work in this case. You can try to use joined inheritance
strategy, this will give you 4 tables, B, C, D and E, but at least the B table will only have the B-columns.

gr. Martin

On 17-02-15 18:19, Mr Cur wrote:
> Hi,
>
> I have the following classes and relations:
>
> A<*>-----------------(hasS)----B
> ^
> |
> ----------------------
> | | |
> C D E
>
> A decomposes into (many) B's, being C, D, and E's.
> Therefore, C, D, and E are subclasses of B.
>
> Since many instances of C, D, and E are generated in application, I want to have them in seperate tables. To do so, I
> defined an MAPPED SUPERCLASS annotation for B. Code generation goes fine.
>
> If I however create an instane of A and C, and try to populatie de decomposition relation between A en C (via B) I get
> the following error:
>
> (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.ValidationException
> Exception Description: [class A] uses a non-entity [class B] as target entity in the relationship attribute [field hasS].
>
> If I ommit the MAPPED SUPERCLASS annotation everything is put in a table B (so C, D, and E) and everything works fine.
>
> Thanks for your help.
>
> Cur.
>

--

With Regards, Martin Taal

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