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CoreData: Inverse relationships not maintained (to-one on one size, to-many on the other, with abstract classes)

Subject: CoreData: Inverse relationships not maintained (to-one on one size, to-many on the other, with abstract classes)
From: Jim Correia <email@hidden>
Date: Tue, 31 May 2005 15:15:51 -0400
Delivered-to: email@hidden
Delivered-to: email@hidden

I have a data model with abstract entities in the hierarchy. The Item object knows about its root container (to one relationship), and the container object knows about its items (too many relationship.)

If I manually set the value for one side of the relationship, the other side isn't maintained automatically. I've built a fictitious app which demonstrates the problem.

Setting either side of the relationship doesn't automatically cause the inverse to update.

NSManagedObjectContext *context = [self managedObjectContext]; id library = [NSEntityDescription insertNewObjectForEntityForName: @"LibraryNode" inManagedObjectContext: context]; id libraryItem = [NSEntityDescription insertNewObjectForEntityForName: @"MP3Item" inManagedObjectContext: context]; id libraryItem2 = [NSEntityDescription insertNewObjectForEntityForName: @"MP3Item" inManagedObjectContext: context];

    [libraryItem setValue: @"Fred" forKey: @"name"];
    [libraryItem2 setValue: @"Bob" forKey: @"name"];

    // Try setting up this side of the relationship

    [libraryItem setValue: library forKey: @"root"];

NSLog(@"%@", libraryItem); NSLog(@"%@", library); NSLog(@"library contains item = %d", [[library valueForKey: @"items"] containsObject: libraryItem]);

    // now try setting up the other side with the second object

[[library mutableSetValueForKey: @"items"] addObject: libraryItem2];

NSLog(@"%@", libraryItem2); NSLog(@"%@", library); NSLog(@"libraryItem2 root = %@", [libraryItem2 valueForKey: @"root"]);


Full example is on my iDisk:

http://homepage.mac.com/jimcorreia/tmp/BrokenInverseRelationships.zip

What am I doing wrong?

Thanks,
Jim


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