Re: Predicate Builder & Fetched Properties
Re: Predicate Builder & Fetched Properties
- Subject: Re: Predicate Builder & Fetched Properties
- From: mmalcolm crawford <email@hidden>
- Date: Tue, 5 Jul 2005 11:57:38 -0700
On Jul 5, 2005, at 10:31 AM, Jeff LaMarche wrote:
So I create my smartlist entity, with one attribute (year), and one
fetched property that references the People object. I go into the
predicate builder and select the birthYear attribute for the left
hand side of the equation, and select "=" for the operator. Now,
there doesn't appear to be any way to specify an attribute from the
smart list entity on the right hand side. I can choose a constant
or another attribute from the Person entity. I've tried using using
$FETCH_SOURCE but it tells me it can't parse it.
<http://developer.apple.com/documentation/DeveloperTools/Conceptual/
XcodeUserGuide21/Contents/Resources/en.lproj/02_04_design_data_model/
chapter_14_section_4.html#//apple_ref/doc/uid/TP40001871-CH273-
DontLinkElementID_70>
see "Right-Hand Side".
Note, though, that a fetched property has at least one distinct
limitation as a "smart list" -- it's not dynamic. After the property
is fetched, it's cached:
<http://developer.apple.com/documentation/Cocoa/Reference/
CoreData_ObjC/Classes/NSFetchedPropertyDesc.html>
If the values on which the result change (in this case, whether the
birthYear is changed because someone made a mistake, or you add or
remove People -- should be "Person"?), this is not reflected in the
fetched property unless you refresh the source object.
mmalc
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