Re: Another Core Data Ivar Setter and Undo Issue
Re: Another Core Data Ivar Setter and Undo Issue
- Subject: Re: Another Core Data Ivar Setter and Undo Issue
- From: Felix Franz <email@hidden>
- Date: Wed, 27 Jun 2007 12:28:14 +0200
Hi Ian,
I found a mail to this list from Kenny Leung very helpful: <http://
www.cocoabuilder.com/archive/message/cocoa/2006/9/2/170502> .
Basically in your setter-method you register a undo-operation to the
ManagedObjectContext's UndoManager.
After CoreData undoes the change your undo-operation is called (which
will simply
send the notification in your example).
For me the whole point of "getting undo for free" with CoreData is
only true if you never put
any code in a NSManagedObject-subclass... (I would be happy to learn
a better way, if anyone
has a better solution speak up! :) )
Cheers,
felix
On Jun 26, 2007, at 11:29 PM, Ian G. Gillespie wrote:
I've searched the archives and couldn't find and answer to my
question, so here goes...
I have Core Data app where one entity say, "Department", wants to
know when there is a change in one of its "Employee" entities
(typical one-to-many relationship example). In the past I
registered Department as an observer for changes in its Employees
for the key paths of interest. This worked fine accept that it led
to some performance issues when a Department was registering for
changes in say 5000-10,000 Employees. To address this I wanted to
use my know observing-notification system using
NSNotificationCenter. I started implementing custom accessors in
my Employee managed object sub-class so that I could post
notifications (as seen below).
The problem is when I undo a change made on an Employee's property
the setMyValue: method is not called again. It is only called when
the user actually changes a value via bindings on the UI. I was
hoping that when Core Data invokes undo that it would call the
appropriate setter value for the property that changed. Is this
the expected behavior of Core Data?
-(void)setMyValue:(NSNumber *)sumValue {
[self willChangeValueForKey:@"myValue"];
[self setPrimitiveValue:sumValue forKey:@"myValue"];
[self didChangeValueForKey:@"myValue"];
//post the notification
[[NSNotificationCenter defaultCenter]
postNotificationName:@"myValueDidChange" object:self userInfo:nil];
}
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