Question

Trying to update some Core Data. The data is actually updating “somewhere”, but its not saving/updating the db.

- (IBAction)Update:(id)sender {


    NSEntityDescription *entityDesc =
    [NSEntityDescription entityForName:@"Preferences"
                inManagedObjectContext:context];

    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    [request setEntity:entityDesc];


    NSError *error;
    NSArray *objects = [context executeFetchRequest:request
                                              error:&error];

    if ([objects count] == 0) {
        // No update, didnt find any entries.

    } else {

        for (NSManagedObject *obj in objects) {           

            [obj setValue:_salesPrice.text forKey:@"value"];
            if(![context save:&error]){
                NSLog(@"Saving changes failed: %@", error);
            }

        }

    }
    //[context save:&error];
}

I’ve tried [context save:&error]; in the commented area, but still no save. I also get no error on save.

Answer 1

You use only 1 NSManagedObjectContext? Your naming convention is not ideal. Usually you would name the entity Preference, since its one object. Try the following code.

CoreDataAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
// This is for completion. Usually you should not get the context from the App Delegate.   
// Its better to pass it from the App Delegate to 
// the initial view controller via a property (dependency injection).

NSFetchRequest *req = [[NSFetchRequest alloc] initWithEntityName:NSStringFromClass([Preferences class])];
    NSError *error = nil;
    NSArray *preferences = [context executeFetchRequest:req error:&error];

// Check error

if ([preferences count] == 0) {
    // No update, didnt find any entries.
} else {
    for (Preferences *preference in preferences) {           
        [preference setValue:_salesPrice.text forKey:@"value"];
    }
}
[context save:&error];
// Check error