Re: compound primary key ("failed to provide new primary keys")
Re: compound primary key ("failed to provide new primary keys")
- Subject: Re: compound primary key ("failed to provide new primary keys")
- From: Chuck Hill <email@hidden>
- Date: Sat, 14 Jun 2008 23:22:36 -0700
On Jun 14, 2008, at 10:32 PM, Gavin Eadie wrote:
Lucky I love learning! Things I learned:
... in WebObjects, if it's difficult, you're doing it wrongly!
Amen. "if it takes more than three lines, you are probably doing it
wrong"
... Chuck is always right (even if he doesn't mention flattening in
his book).
After much internal debate we decided to only mention the merely
obvious and eliminate the blindingly obvious. :-P
... Apple's documentation for EOF at WO version 4.5 rocks!
Sadly, this true. The 4.5 docs + updates for Eclipse would be great.
Alas, I think this task is now up to the community. There was a lot
of discussion at WOWODC and WWDC on how we might best do this. I
heard a lot of good ideas. I expect there will be some discussion of
them in the near future once everyone recovers from seven straight
days of conferencing.
... Start with the model and let the database take care of itself.
Yep, focus on what you want to get done, not on how you thing you
might need to do it.
WebObjects standard flattened many-to-many relationship was what I
was missing. I was focused on the legacy tables I was working with
and they were muddying the waters. My new code is now working
perfectly, is smaller than before, easier to read and I'm happy
again. Thanks to those who helped, thanks to those who didn't
wonder out loud how I ever got this far without comprehending some
of the simpler aspects of EOF ... Gav
Rest assured, there is always one more quirk waiting to be discovered.
Chuck
On Jun 14, 2008, at 7:08 PM, Chuck Hill wrote:
Why do they even have a class? If it is just two keys, just use an
EOGenericRecord and flatten the relationships. Then all you need
to do is to say user().addToFavoriteAdverts(ad); I don't think you
should even need the addObjectToBothSidesOfRelationshipWithKey.
That might cause too much faulting for popular ads.
The real world model is a bulletin board of advertisements whose
users may select some favorite ads that they want to keep track
of. So a boring ad will have no connecting Select, and someone
who is not a frequent visitor may have no connecting Select. On
the other hand a really interesting ad may have dozens of Selects
(dozens of people putting it in their favorites), and a busy user
may have dozens Selects (ads they are tracking). Any one Select
contains only the pkeys of the Advert and Author (user) it
relates. This may have been modeled badly seven years ago, but
it's what I have to work with !! Gav
Seems to me like it should be no trouble at all.
Chuck
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