Expected Extent Behavior?

[Brian Latimer <bl...@apcc.aspca.org>]

I have an Interface "I"

It has implementing classes A, B, and C

Classes B and C both extend class A and have a super reference to it.

If  use the following:
<class-descriptor class="I">
        <extent-class class-ref="A" />
    </class-descriptor>

when I search via getCollectionByQuery for instances of "I" then I get 
back instances of B and C with all their data and no A objects that 
duplicate the id's of these objects.  (all instances of A are really 
either B or C, so this is what I want anyway)

Previously (OJB1.01 and less) I seem to recall getting back both an A 
and a B or and A and a C object for each id when I attempted queries of 
this sort. 

If instead I use:
<class-descriptor class="I">
        <extent-class class-ref="C" />
        <extent-class class-ref="B" />
    </class-descriptor>

then I get null values for all the A class fields in the returned class 
B and C objects.


Is this the expected behavior?  Should the query be extent aware like this?

I just thought I'd ask for clarification and if this was odd behavior 
point it out.

thanks







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Re: Expected Extent Behavior?

[Armin Waibel <ar...@apache.org>]

Hi Brian,

Brian Latimer wrote:
> I have an Interface "I"
> 
> It has implementing classes A, B, and C
> 
> Classes B and C both extend class A and have a super reference to it.
> 
> If  use the following:
> <class-descriptor class="I">
>        <extent-class class-ref="A" />
>    </class-descriptor>
> 
> when I search via getCollectionByQuery for instances of "I" then I get 
> back instances of B and C with all their data and no A objects that 
> duplicate the id's of these objects.  (all instances of A are really 
> either B or C, so this is what I want anyway)

This is the expected behavior.
Take care not to mix different inheritance strategies (is not 
supported). This case (table-per-subclass inheritance + interface 
extent) should work.

>
> Previously (OJB1.01 and less) I seem to recall getting back both an A 
> and a B or and A and a C object for each id when I attempted queries of 
> this sort.
> If instead I use:
> <class-descriptor class="I">
>        <extent-class class-ref="C" />
>        <extent-class class-ref="B" />
>    </class-descriptor>
> 
> then I get null values for all the A class fields in the returned class 
> B and C objects.
> 
> 
> Is this the expected behavior?  Should the query be extent aware like this?
>

In further OJB versions there was a bug related to the "table per 
subclass" inheritance (multiple joined tables bug) which only returns 
instances of the base class (see release-notes "known issues" section of 
previous versions). Think that the described behavior could be a side 
effect of this bug.

regards,
Armin


> I just thought I'd ask for clarification and if this was odd behavior 
> point it out.
> 
> thanks
> 
> 
> 
> 
> 
> 
> 
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> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
> 
> 


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