On Aug 3, 2010, at 13:37, Ignacio Enriquez wrote: > User can create files and folders (they don't have to be real folders/files). > Folders can contain files or other folders > Files have: > title, > summary and > 8 children > Each child also has a title and a summary and could have 8 children > (optionally) > This could be as many levels (recursive) as the user desires. > I am not sure how to express this in CoreData. Could someone give a hand here? > > This is what I've done: http://yfrog.com/j2o1op > > "Child" entity with "title" and "summary" attributes and "children" > (to-many) relationship pointing to "Child" entity > "File" entity with "isDirectory" and "name" attributes and "files" > (to-many) relationship pointing to "File" entity and "children" > (to-many) relationship pointing to "Child" entity. > > Doing that gets me a warning: > File.children -- to-many relationship does not have an inverse: this > is an advanced setting (no object can be in multiple destinations for > a specific relationship) > Why is that? I've tried to set the inverse relationship but there are > no options to choose from.
According to this description, you're not missing one inverse, you're missing 3 of them: File.parentFile, Child.parentChild and Child.parentFile. If that sounds a bit weird that's because your design is a double tree structure with 2 entities in it. So one approach is to add the 3 missing 1-1 relationships. (A Child object has a parentChild or a parentFile but not both. Or maybe it can have both -- your description doesn't exactly rule out that this might be your intention.) The kind of structure you're trying to model would be easier if Core Data allowed mixed entities in a relationship, but it doesn't, so you have to the long way round to get the results you want. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
