Re: Core Data Binding question: How to implement unidirectional or read-only binding
Re: Core Data Binding question: How to implement unidirectional or read-only binding
- Subject: Re: Core Data Binding question: How to implement unidirectional or read-only binding
- From: Scott Anguish <email@hidden>
- Date: Sun, 23 Apr 2006 20:49:24 -0400
On Apr 23, 2006, at 7:32 PM, Peter Bates wrote:
Before I do things the hard way, just thought I'd ask of those more
experienced in the core data and bindings worlds if there might be
an easy way around this problem:
This isn't a Core Data related question and you used it in the
subject. I happen to know this drives mmalc bananas.. :-) Good on you.
I have a core data application in which a comboBox is bound to two
array controllers. The combo boxes' content is bound to the
controller A arrangedObjects, the contentValue is bound to
controller A arrangedObjects.name key, and the value is bound to
arrayController B's selection.name. The problem is that I'm
allowing the user to enter a partial name in the comboBox and using
a delegate method to fetch matching names, setting the fetched
array as the comboBoxes' arrayController A's content.
The hitch is that the partial name typed by the user is propagated
back to the object. I think what I really need here is a
unidirectional or read only binding.
not really. Read-only bindings aren't editable. If you change the
value in the model, that change is reflected in the UI.
Otherwise I'll probably have to construct a parallel array based
on the fetched data and use the parallel array as the
arrayController's content. I have a feeling this would be picking
the hard and error prone way to accomplish the desired end. I'll
appreciate any advice. I've been picking through the
documentation, searching the archives etc., but haven't yet
recognized the answer if it's there.
that's how I'd do it. I've done this before using the KVC operators
to generate a unique array containing only the distinct names. BUT,
it causes a cascade of KVO updates as the data is loaded and makes
load times excessive. that's why I went to the other method.
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