How to delete an object from RestKit managed object store

Question

I'm using RestKit 0.2 to get a JSON file from my server and map the objects to my CoreData stack (analog to the TwitterCoreData example).

In the first request, I get the following result: Artist1, Artist2, Artist3.

In the second request, one artist is outdated and the result looks like this: Artist1, Artist3.

Now the Artist2 should be deleted from my local store and disappear in my UITableView. However, I can't find a way to delete the Artist2 from my local storage.

How do I delete an object in RestKit 0.2 from a managed object store?

This is what I am doing:

#pragma mark - Data methods
- (void)fetchResults {
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"Artists"];
NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:@"ordernr" ascending:YES];
fetchRequest.sortDescriptors = @[descriptor];
NSError *error = nil;

// Setup fetched results
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                                                    managedObjectContext:[RKManagedObjectStore defaultStore].mainQueueManagedObjectContext
                                                                      sectionNameKeyPath:nil
                                                                               cacheName:nil];
[self.fetchedResultsController setDelegate:self];
BOOL fetchSuccessful = [self.fetchedResultsController performFetch:&error];

if(fetchSuccessful){
    data = [self.fetchedResultsController fetchedObjects];
    [_tableView reloadData];
    NSLog(@"Fetched artists: %i", [[self.fetchedResultsController fetchedObjects] count]);
}
}

- (void)loadData {
[[RKObjectManager sharedManager] getObjectsAtPath:@"/artists.php" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {


     NSLog(@"Fetched artists: %i", [[mappingResult array] count]);

    for (id object in data) {
        if (NO == [[mappingResult array] containsObject:object]){
            NSLog(@"DELETE 1 object...");
            //HOW TO DELETE THE OBJECT HERE??
        }
    }

    [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"ArtistsLastUpdatedAt"];
    [[NSUserDefaults standardUserDefaults] synchronize];

    [self fetchResults];

} failure:^(RKObjectRequestOperation *operation, NSError *error) {
    RKLogError(@"Load failed with error: %@", error);
}];
}

could you please add a link to the `TwitterCoreData` example? — Azulflame, Jan 11 '13 at 16:51

score 0 · Accepted Answer · answered Jan 12 '13 at 13:14

0

Try the following:

NSManagedObjectContext *context = object.managedObjectContext;

[context deleteObject:object];

NSError *error;
if (![context save:&error]) {

NSLog(@"delete error");

// Handle the error, update UI etc.

}

answered Jan 12 '13 at 13:14

Alex

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But after app restart the value is default again. There's no error while saving, but it seems it didn't save correctly? – TimE90 Feb 27 '13 at 15:20
You should also perform a save on the [persistenStoreManagedObjectContext](http://restkit.org/api/latest/Classes/RKManagedObjectStore.html#//api/name/persistentStoreManagedObjectContext) since the object's managedObjectContext is a child of it. – Alex Feb 27 '13 at 16:58

score 0 · Answer 2 · answered May 06 '14 at 11:03

I firstly followed suggestion from Alexander's answer but it was deleting the object only from the current context. Once the app was restarted, the object was fetched from core data again.

Therefore, you should save changes to persistent store:

NSManagedObjectContext *context = objectToBeDeleted.managedObjectContext;
[context deleteObject:objectToBeDeleted];
NSError *error;
if (![context saveToPersistentStore:&error]) {
    NSLog(@"delete error %@", [error localizedDescription]);
}

How to delete an object from RestKit managed object store

2 Answers2