On 28-May-09, at 12:56 PM, Dave Fernandes wrote:
When the instance variable changes in your custom class, you can
call willChangeValueForKey: and didChangeValueForKey: for the entity
that contains your custom class.
I haven't ever had to do this, but it is the first thing I would try.
Thanks - you know it's funny I was just trying something like this,
and it seems to work - partly.
In the custom entity class I enumerated all the keys in the dictionary
ivar (on fetch and insert), adding appropriate observers for each
one. This can be used to fire observeValueForKeyPath: in the entity's
class, where I tried calling will/didChangeValueForKey: for the
persistent representation of the custom class. This caused an
infinite loop where these change notifications kept triggering the
observer, but I think I'm close.
Maybe I can use the change dictionary in observeValueForKeyPath: to
break out of the loop when there's no real change.
Rick
On May 28, 2009, at 12:34 PM, Rick Hoge wrote:
On 28-May-09, at 10:39 AM, Keary Suska wrote:
On May 28, 2009, at 7:03 AM, Rick Hoge wrote:
I have a core data (doc-based) app in which one of the entities
includes a custom object as a persistent attribute. The custom
object class implements NSCoding, and these objects are saved to
the core data store with no problem (they are read back correctly
etc). Instance variables of the custom object are exposed in the
user interface, and can be edited by the user.
The problem I have is that changes to instance variables of these
custom objects are not reported to the managed object context, so
the core data document is not flagged as dirty and, even if I
force a save by adding an entity and invoking save, the modified
custom object is not saved (if I quit and reload the old ivar
values are loaded).
http://developer.apple.com/documentation/Cocoa/Conceptual/CoreData/Articles/cdNSAttributes.html#/
/apple_ref/doc/uid/TP40001919
Thanks - I'd looked at this, and following the information there is
what allowed me to insert and display custom object attributes.
The documentation shows examples in which an attribute of type
NSColor can be set and archived. My problem is that I'm dealing
with a complex object type (I have what I think are good reasons
for doing this) and I need to flag the context as dirty if an ivar
of the custom object is modified.
Specifically my entity has a 'transformable' attribute for which
the values are a custom object class, and this object class has an
ivar that is an NSMutableDictionary. The user can modify entries
in this dictionary, and I would like this to cause the context to
be flagged as dirty and to have the custom object flagged to be
updated in the persistent store.
Hope this clarifies things, and thanks again for the suggestion.
Rick
Keary Suska
Esoteritech, Inc.
"Demystifying technology for your home or business"
(43092.6825)
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