How to use the "ALL" aggregate operation in a NSPredicate to filter a CoreData-based collection

objective-c ios core-data nspredicate
Stian Høiland picture Stian Høiland · Mar 14, 2011 · Viewed 8.4k times · Source

Based on the data model below

dataModel

And based on user input I create a NSSet of managedObjects of entity Tag called selectedTags.

My problem:

[NSPredicate predicateWithFormat:@"ANY entryTags IN %@", selectedTags];

... this will return any Entry with at least one entryTag that is in the selectedTags set.

I want something along the lines of:

[NSPredicate predicateWithFormat:@"ALL entryTags IN %@", selectedTags];

... notice the only change is the "ANY" to "ALL". This illustrates what I want, but does not work.

To formulate the outcome I expect:

I'm looking for a solution that will return only Entries who's entryTags are all in the selectedTags list (but at the same time, if possible, not necessarily the other way around).

To further illustrate:

(tag)Mom
(tag)Dad
(tag)Gifts

(entry)she is a she.....(tag)mom
(entry)he is a he........(tag)dad
(entry)gifts for mom...(tags:)mom, gifts
(entry)gifts for dad.....(tags:)dad, gifts

If selectedTags contains "mom" and "gifts", then the entry "gifts for dad" will show up, since it has the tag "gifts". I'd rather have it not show :)

Answer

Stian Høiland picture Stian Høiland · Mar 31, 2012

This is the definite answer so far:

[NSPredicate predicateWithFormat:@"SUBQUERY(entryTags, $tag, $tag IN %@).@count = %d", selectedTags, [selectedTags count]];

B-E-A-U-T-I-F-U-L.

Thanks to Dave DeLong.

Related questions

NSPredicate Exact Match with String

I have a NSPredicate like this: NSPredicate *predicate = [NSPredicate predicateWithFormat:@"entity.name CONTAINS %@", myString]; But that will return anything which contains that string. For example: If my entity.name's where: text texttwo textthree randomtext and the myString was text then …

Read More
NSPredicate compare with Integer

How can I compare two NSNumbers or a NSNumber and an Integer in an NSPredicate? I tried: NSNumber *stdUserNumber = [NSNumber numberWithInteger:[[NSUserDefaults standardUserDefaults] integerForKey:@"standardUser"]]; fetchRequest.predicate = [NSPredicate predicateWithFormat:@"userID == %@", stdUserNumber]; Well, this doesn't work ... anyone has an idea how …

Read More
How to fetch a single object from Coredata using a predicate

I am trying to fetch a single object from my coredatabase, however it keeps returning null. My method is based off another method which returns every value from the coredata object that I am accessing.. I have never tried this …

Read More