Re: How do I add additional Attributes to a Core Data Entity?
Re: How do I add additional Attributes to a Core Data Entity?
- Subject: Re: How do I add additional Attributes to a Core Data Entity?
- From: Charles Haron <email@hidden>
- Date: Thu, 21 Jul 2005 16:38:29 -0600
I'm having the same problem after adding a new attribute, except I'm
getting the following error:
[NSArrayController presentError:]: selector not recognized [self =
0x36b880]
2005-07-21 16:20:32.075 CoreDataTest[474] *** NSRunLoop ignoring
exception '*** -[NSArrayController presentError:]: selector not
recognized [self = 0x36b880]' that raised during posting of delayed
perform with target 392290 and selector 'invokeWithTarget:'
I'm new to Cocoa and Core Data, but I've read repeatedly that Core
Data relies on key-value coding. It seems to me that one of the
benefits of using a key-value mechanism is to free you from order
dependancy.
Why do Entities rely on order? And more importantly, why doesn't the
data modeler allow you to change the entity order?
Charles
On Jul 21, 2005, at 10:27 AM, Charilaos Skiadas wrote:
On Jul 21, 2005, at 11:00 AM, Andrew Sage wrote:
I have a set of Core Data Entities which each have several
Attributes.
This Data Model has been used for the first version of my software
and I now
have a large amount of data built around it.
The problem is that I tried to add an additional Attribute to one
of the Entities and it
messed everything up. Due to the Attribute's being order by name
in the Entity in the Data Model it appears that my new Attribute
has gone into the middle and values loaded from file are now
ending up in the wrong Attributes.
Is this meant to happen? Is there any way around this or is there
some kind of
versioning that can be used to migrate data from the old model to
the new one?
The CoreRecipes example at http://developer.apple.com/samplecode/
CoreRecipes/CoreRecipes.html
has a detailed example on how to migrate your data. Look under
"Sample Applications/Migration". I haven't personally used it, but
it seems to be what you want.
Thank you.
Haris
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