Re: Core Data and @count keypath
Re: Core Data and @count keypath
- Subject: Re: Core Data and @count keypath
- From: GbT <email@hidden>
- Date: Wed, 8 Feb 2006 10:04:29 +0100
Thanks. Now it works perfectly.
Anyway I'd like to display the count in the same way Mail does for
every folder ... with a grey circle and the number of unread items
inside... I have to put it in a nstablecolumn... should I subclass
NSTableColumn or what is the best way to do this?
2006/2/7, John R. Timmer <email@hidden>:
> You have to bind to a value that's read/write. @count is read only.
> If you need to bind to it, make a managed object key like arrayCount
> that returns the count in the getter method, and does nothing in the
> setter method.
>
> JT
>
> On Feb 7, 2006, at 2:14 AM, GbT wrote:
>
> > Hi,
> > I have a core data app with some entities, the entity A has a to-many
> > relationship with another entity B. I use an nstreecontroller for A
> > and want to display the number of records for the relationship A-->>B,
> > but if I put relationshipToB.@count in the model key path in the
> > bindings I obtain this message:
> >
> > *** NSRunLoop ignoring exception '[<_NSFaultingMutableSet 0x3c5d30>
> > addObserver:forKeyPath:options:context:] is not supported. Key path:
> > @count' that raised during posting of delayed perform with target
> > 37e980 and selector 'open:'
> >
> > The selector open is related to the drawer... but the addObserver
> > thing isn't clear to me...
> > My entities are all subclassed by NSManagedObject.
>
> ____________________________________
> Science writer, Ars Technica (among other things)
> http://arstechnica.com/journals/science.ars
>
>
>
>
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