Re: EOQualifier or...?
Re: EOQualifier or...?
- Subject: Re: EOQualifier or...?
- From: Chuck Hill <email@hidden>
- Date: Thu, 23 Apr 2009 09:20:03 -0700
On Apr 22, 2009, at 3:21 PM, John Ours wrote:
I have a situation where I have an entity "Item" that is related to
many "Picture" items. I'm trying to fetch all "Items" that have no
related "Pictures"...in sql I would write a query like:
SELECT * FROM Item i
LEFT JOIN Picture p ON i.id = p.itemID
WHERE p.id is null
In other words I'd like to select all where Item.pictures.count ==
0. What's the easiest / best / most correct way to do this with EO?
Plain EOF is probably not going to do this. You could try an Equals
qualifier with null or an empty array and see if you get lucky.
Otherwise, you need to look into the additional qualifiers in Wonder
and the Houdah frameworks. None of these are super well documented as
to all of their possibilities, so you often need to poke around in
them and sometimes come at your problem from a different angle. I
don't recall off the top of my head which combination will get you
what you want.
Chuck
--
Chuck Hill Senior Consultant / VP Development
Come to WOWODC'09 in San Fran this June!
http://www.wocommunity.org/wowodc09/
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