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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: Circle references
Date Wed, 15 Apr 2009 12:50:45 GMT
Yeah you described the cause correctly. Now forgetting about Cayenne  
for a sec, is there even a way to save it with just SQL INSERTs  
without violating the constraints?

Usually there isn't and the commit has to be split into INSERT ...  
VALUES (NULL /* null FK */...) and an UPDATE. Cayenne can't do it  
automatically, so you can either manually split it to 2 transactions,  
or figure a way to configured "deferred constraint checking" on your  
DB (some DB's allow that), or drop the FK constraint for this one  
relationship in DB.

Andrus

On Apr 15, 2009, at 3:37 PM, Andrey Razumovsky wrote:

> Hi,
>
> I've got three entities, A, B, and C and three to-one relationships  
> (A->B,
> B->C, C->A). When I fire code like that:
>
> A a = context.newObject(A.class);
> B b = context.newObject(B.class);
>
> a.setToB(b);
> context.commitChanges();
>
> I *sometimes* get SQL exception at commit, saying that object in B  
> does not
> exist when inserting A, i.e. Cayenne is insering records in wrong  
> order.
> Seems that it just can't define order of commits because of circle
> references. Can I somehow help Cayenne solve this puzzle? (I think I  
> can
> even sacrifice some of reverse (to-many) relationships.
> And what's the algorithm of sorting entities before commit?
>
> Thanks,
> Andrey


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