Re: empty relationship qualifier question
Re: empty relationship qualifier question
- Subject: Re: empty relationship qualifier question
- From: Pierre Bernard <email@hidden>
- Date: Fri, 04 Jul 2008 23:17:01 +0200
Hi!
Actually, EOKeyValueQualifier("tracks",
EOQualifier.QualifierOperatorEquals, NSKeyValueCoding.NullValue)
should work just fine.
Please report back if it doesn't. I'd like to know.
An alternative - usually used only for more complex cases - would be
to use the ExistsInRelationshipQualifier from my Houdah WebObjects
frameworks project.
Best,
Pierre Bernard
Houdah Software s.à r.l.
On 4 Jul 2008, at 10:32, Michael Bushkov wrote:
Hi,
I have quite simple task, but I don't see any proper solution. The
task is as follows:
I have 2 entities - Song and Track. Song has a one-to-many
relationship to Track (Song->tracks). And I need to fetch all songs
which have no tracks. That's all - plain and simple.
I've looked through the list of available qualifiers and even started
to write one by myself, but it looks like an overkill for such a
simple task. The straightforward solution, that I see is to cache
number of tracks in Song entity (make a Song->tracksNumber field). But
it looks like modifying model for implementation purposes (this
however can be very effective on large datasets, because such database
structure doesn't require using subqueries to find songs with no
tracks).
Any suggestions are greatly appreciated )
--
With best regards,
Michael Bushkov
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Pierre Bernard
http://www.bernard-web.com/pierre
http://www.houdah.com
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