NSPredicate for a Core Data Search

Question

I have 3 NSManagedObjets; Person, Stuff, and Collection.

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I want to use a NSPredicate to get a list of all Collections that ThePerson has.

Example: Scott has objectA and objectB which are in collection Letters and object1 which is in collection Numbers.

I want to be able to do a fetch request and get back collection Letters and Numbers.

I tried:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY stuffs.persons == %@", person];

And:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SUBQUERY(stuffs, $s, ANY $s.persons == %@)", scott];

Any suggestions?

score 1 · Accepted Answer · edited May 23 '17 at 12:30

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Your SUBQUERY syntax is wrong (for a full explanation, see this answer or this answer). It should be something like:

SUBQUERY(stuffs, $s, ANY $s.persons == %@).@count > 0

edited May 23 '17 at 12:30

Community

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answered Aug 28 '13 at 22:13

Dave DeLong

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score 1 · Answer 2 · answered Aug 28 '13 at 22:28

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Since it seems that you already have a reference to a ThePerson object, you don't need to do a fetch or use a predicate. You can traverse the relationships you've declared to get the collections. You can get all of the Collections that ThePerson has by using:

NSSet *collections = [person valueForKeyPath:@"stuffs.collections"];

answered Aug 28 '13 at 22:28

Tom Harrington

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There is another condition that I forgot to mention: Scott's Letter `Collection` may contain objectA and objectB, while Jen's Letter Collection may only contain objectA. With that requirement, I don't believe this solution would work? Or would I be wrong? I'm sorry I didn't state this in the question originally. – Padin215 Aug 29 '13 at 13:31

NSPredicate for a Core Data Search

2 Answers2