Re: Core Data: Cross-model relationships
Re: Core Data: Cross-model relationships
- Subject: Re: Core Data: Cross-model relationships
- From: Scott Stevenson <email@hidden>
- Date: Sun, 14 Oct 2007 23:47:53 -0700
On Oct 11, 2007, at 11:40 PM, Ian Joyner wrote:
When I setup a fetched property for state in my document entity (in
Xcode modeller) it needs the destination set – however, the
destination popup only shows entities in the current model. What I
want (I think) is a predicate something like:
State.id == $FETCH_SOURCE.state_id
I think you're far better off simulating this in code rather than
trying to represent it in the model in any form. In other words,
focus on getting the *values* transferred between stores rather than
actual managed objects.
I'm guessing you have something long the lines of key/value pairs for
a dropdown in the UI -- with the options being defined in the prefs
but selectable in each document?
Create a method that fetches the managed objects from the prefs store
and converts them into generic NSDictionary objects which can be used
to populate the UI in the document. If the prefs change, post a
notification so that all open documents can sort it out -- and do the
same when you open a document.
You can generate UUIDs if you want to assign unique ids to items you
create in prefs. But keep in mind the basic issue with all of this is
that the document themselves are not portable. That is, you can't
take them to another machine since the prefs will be missing.
I know this is all somewhat vague, but I have no idea what the code
looks like. :)
- Scott_______________________________________________
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