Filter childs not parents of relationship Coredata

Question

I'm trying to filter the child of relationship in coredata but the problem is that Coredata filters by parent and this is correct but it isn't filtering the childs.

Model:

Volumen <-->> MusicScore

I want filter the musicscore rows by volumen.

My NSPredicate is that:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SUBQUERY(relation_music_score, $musicscore, ANY $musicscore.nameMusicScore CONTAINS[cd] %@).@count > 0", searchStr];

self.collectionVolumen = [BOIVolumen MR_findAllWithPredicate:predicate];

CoreData get me all volumes that contains the name of music score searched but I want the all volumens with only the music score searched not all music score.

Example:

Volumens
  name = "One",
  etc..
  relation_music_score = NSOrderedSet

     Music Score (1)
       name = "One"

     Music Score (2)
       name = "two"

Volumens
  name = "Two",
  etc..
  relation_music_score = NSOrderedSet

     Music Score (3)
       name = "three"

     Music Score (4)
        name = "four"

When I'm searching the music score with name "two" I want this result:

Volumens
  name = "One",
  etc..
  relation_music_score = NSOrderedSet

Music Score (2)
  name = "two"

And the previos NSPredicate get me:

Volumens
  name = "One",
  etc..
  relation_music_score = NSOrderedSet

Music Score (1)
  name = "One"

Music Score (2)
  name = "two"

EDIT:

I'm trying the filter the relationship with this predicate and code:

  for (int i = 0; i < [self.collectionVolumen count]; i++) {
        BOIVolumen *volumen = [self.collectionVolumen objectAtIndex:i];
        NSOrderedSet *musicStore = [[self.collectionVolumen objectAtIndex:i] relation_music_score];

        NSPredicate *filterMusicScore = [NSPredicate predicateWithFormat:@"nameMusicScore CONTAINS[cd] %@", searchStr];
        NSOrderedSet *musicStoreTemporal = [musicStore filteredOrderedSetUsingPredicate:filterMusicScore];

        volumen.relation_music_score = musicStoreTemporal;
    }

and always I get this error The left hand side for an ALL or ANY operator must be either an NSArray or an NSSet. I was finding and I didn't found nothing.

Mundi Mundi · Accepted Answer · 2014-12-26T16:03:43

Your predicate, though overly complicated, is working. You are getting the correct selection of Volumen entities. The found instance of course still has all the available relationships, so you have two choices:

You either filter the relationships again e.g. with filteredSetUsingPredicate:,
or you fetch the MusicScore entities in the first place rather than the Volumen entities.

I think the second option is what you want.

Filter childs not parents of relationship Coredata

1 Answers