Geek Answers Handbook

Master Data Relationship Rule - Nullify + Cascade

Entities:

  • Video
  • Playlist item
  • Playlist

Relationship:

  • Video is optional for many for a playlist item, and the delete rule is nullify
  • List of playlists - for many, at least one element of the playlist, and the deletion rule is nullify
  • A playlist item is required for one for the video, and a delete rule is nullify
  • The playlist item is required for one for the playlist, and the deletion rule is nullify.

In the Playlist object, I did not find the connection / set playlistItem. Instead, I have an undefined transition attribute called "video", which is an array of Video objects generated by sorting a set of playlist items. There are no links between the playlist and the Video objects.

I am having problems saving a modified instance of a playlist in the context of a managed entity.

From the .m playlist (subclass of NSManagedObject):

- (BOOL)validatePlaylistItems:(NSSet **)playlistItems error:(NSError **)outError
{
    NSArray *currentVideos = [self videos];
    NSArray *persistedVideos = [self videosFromPlaylistItems];

    if ([currentVideos isEqual:persistedVideos]) {
        return YES;
    }

    NSManagedObjectContext *context = [self managedObjectContext];
    for (FHPlaylistItem *pi in *playlistItems) {
        [context deleteObject:pi];
    }

    NSArray *videos = [self primitiveVideos];
    NSUInteger count = [videos count];
    for (int i = 0; i < count; i++) {
        FHPlaylistItem *pi = [FHPlaylistItem playlistItemWithVideo:[videos objectAtIndex:i]
                                                          forIndex:i
                                    insertIntoManagedObjectContext:[self managedObjectContext]];
        [self addPlaylistItemsObject:pi];
        [pi setPlaylist:self];
    }

    return YES;
}

What I'm trying to do here is only updating the set of playlist items when the MOC needs to be saved, since you see that the operation is expensive - O (N * 2). When you first launch the application, MOC saves only a fine. However, subsequent changes to the video attribute in Core Data lead to many errors:

Core Data: annotation: repairing missing delete propagation for to-many relationship playlistItems on object <FHPlaylist: 0x6c27eb0> (entity: Playlist; id: 0x6c26d40 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/Playlist/p19> ; data: {
    accountID = 0;
    lastFetched = "2012-03-31 20:05:08 +0000";
    name = Featured;
    playlistID = 1441335931001;
    playlistItems =     (
        "0x6c34be0 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B2>",
        "0x6c34320 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p16>",
        "0x6c310c0 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B3>",
        "0x6c35570 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B5>",
        "0x6c34ca0 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B6>",
        "0x6c34310 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p8>",
        "0x6c28a90 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B4>",
        "0x6c34350 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p29>",
        "0x6c34220 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p2>",
        "0x6c34330 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p20>",
        "(...and 1 more...)"
    );
    playlistType = 0;
    referenceID = OKFFeaturedPlaylist;
    shortDescrip = "This is so descriptive! OMG!";
    thumbnailURL = nil;
    videos = "(...not nil..)";
}) with bad fault 0x6c34320 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p16>
Core Data: annotation: repairing missing delete propagation for to-many relationship playlistItems on object <FHPlaylist: 0x6c27eb0> (entity: Playlist; id: 0x6c26d40 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/Playlist/p19> ; data: {
    accountID = 0;
    lastFetched = "2012-03-31 20:05:08 +0000";
    name = Featured;
    playlistID = 1441335931001;
    playlistItems =     (
        "0x6c34be0 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B2>",
        "0x6c310c0 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B3>",
        "0x6c35570 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B5>",
        "0x6c34ca0 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B6>",
        "0x6c34310 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p8>",
        "0x6c28a90 <x-coredata:///PlaylistItem/t9EAFBC87-5E16-4053-984F-881CCD9C1F0B4>",
        "0x6c34350 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p29>",
        "0x6c34220 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p2>",
        "0x6c34330 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p20>",
        "0x6c34340 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p27>"
    );
    playlistType = 0;
    referenceID = OKFFeaturedPlaylist;
    shortDescrip = "This is so descriptive! OMG!";
    thumbnailURL = nil;
    videos = "(...not nil..)";
}) with bad fault 0x6c34310 <x-coredata://BCB69D8E-8393-4A2A-AF5D-0AA1872CE2B4/PlaylistItem/p8>
Etc. Etc. Etc.

, . " ", , nullify . ? . Apple Core , Video Playlist, .

Cascade -

, , Core Data .

for (FHPlaylistItem *pi in *playlistItems) {
    [pi setVideo:nil];
    [pi setPlaylist:nil];
    [context deleteObject:pi];
}

a > : , . ( , ?)

+5
4

, [[self managedObjectContext] processPendingChanges] , .

, , , .

,

.

+10

-processPendingChanges . -prepareForDeletion NSManagedObject "-":

- (void)prepareForDeletion {
    [[[self owningEntity] mutableSetValueForKey:@"ownedEntities"] removeObject:self];
}

, . , . , -, , .

+1

Playlist /set playlistItem. undefined, "", , .

, . , Video. , videos, . videos Playlist h, ( ) , , videosSorted ( ).

Also, be sure to clear the model whose relationships are mutually opposed.

0
source

using executeBlock function fixed this for me:

[context performBlock:^{

// delete objects

// save context

}];
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source

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