unique properties using Core Data
unique properties using Core Data
- Subject: unique properties using Core Data
- From: C Thomas <email@hidden>
- Date: Wed, 13 Jul 2005 11:29:42 -0500
Core Data uses so much of the database paradigm that I expected to
see an option to choose to make a property unique... but failing
that, I am trying to implement uniquing myself...
My entity's name property needs to be unique within the managed
object context. So, I'd like to validate it before I insert it, and
'validateForInsert' seems like the logical way to do that.
My problem is that I can't even set the property until I've already
inserted the NSManagedObject into the context using (id)
initWithEntity:(NSEntityDescription*)entity
insertIntoManagedObjectContext:(NSManagedObjectContext*)context. By
then, it's too late - I've already inserted it.
Can somebody explain how to use validateForInsert?
In case i'm about to be advised to use validateValueForKey instead, I
can't do that since core data seems to call that method for each
object upon exit - to make sure that all of the objects are in a
valid state, I suppose.
Is there some sort of context-dependant method like
validateValueForInsert or something like that? For a property that
must be unique, the property can be valid for insert, but once it's
inserted it's no longer a valid property to insert.
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