Re: Strange error message

Hi Chuck,


On Tuesday, Oct 8, 2002, at 20:21 Europe/Paris, Chuck Hill wrote:

> What database are you using?  EOF with Oracle or FrontBase usually 
> uses a sequence generator on (in your example) RootClass to generate 
> the PK for objects at or below that root.  You should be able to do 
> the same thing.

I am using FrontBase.
I now realize that I have not assigned external entity names to 
entities like "RootClass".
Do you think it could be the root of my problem?

Camille




> Camille Troillard wrote:
>
>> Chuck, that's it!
>> Now I perfectly understand because my model used to work when I was 
>> using unique PKs.
>> I guess I must rollback to the first implementation ... and find a 
>> way to generate PK shorter than the default implementation.
>> Thanks to everybody that helped me to solve the problem!!!
>> Camille
>> On Tuesday, Oct 8, 2002, at 19:59 Europe/Paris, Chuck Hill wrote:
>>> Ah Ha!  I know the answer.  EOs in an inheritance hierarchy MUST 
>>> MUST MUST have unique primary keys.  That is the only way that EOF 
>>> can differentiate which class an object is.  In your case
>>>
>>> RootClass ----> EntityA
>>>           ----> EntityB
>>>
>>> No object of EntityA, EntityB (or RootClass if not abstract) can 
>>> have the same PK.   If EOF fetches an instance of EntityA with a PK 
>>> of 1000, and then fetches an instance of EntityB with a PK of 1000 
>>> it will think (because the EOGlobalID is the same) that the EntityB 
>>> instance is actually the EntityA instance.
>
>
> -- 
>
> Chuck Hill                                 [email protected]
> Global Village Consulting Inc.             
> http://www.global-village.net
>
>
>