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PODuplicate records in Core Data on fetch
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  1. PODuplicate records in Core Data on fetch
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    copied!<p>Folks,</p> <p>I've got a bit of a puzzler involving Core Data in my iPhone project. During the viewDidLoad method in two separate view controller instances I call the following method:</p> <pre><code>- (NSFetchedResultsController *)getStudentResults:(NSString *)classRoom forWeekStarting:(NSDate *)startDate andEnding:(NSDate *)endDate { AttendanceAppDelegate *appDelegate = (AttendanceAppDelegate *)[[UIApplication sharedApplication] delegate]; NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Student" inManagedObjectContext:[appDelegate managedObjectContext]]; int secondsInAWeek = 60 * 60 * 24 * 7; NSDate *today = [[NSDate alloc] init]; NSDate *nextWeek = [[NSDate alloc] initWithTimeIntervalSinceNow:secondsInAWeek]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(student.classRoom like %@) AND (dateTime &gt;= %@) AND (dateTime &lt;= %@)", classRoom, startDate, endDate]; [request setPredicate:predicate]; [request setEntity:entityDescription]; NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"dateTime" ascending:YES]; NSArray *descriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:descriptors]; [descriptors release]; [sortDescriptor release]; [nextWeek release]; [today release]; NSFetchedResultsController *fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:[appDelegate managedObjectContext] sectionNameKeyPath:nil cacheName:@""]; NSError *error; if (![fetchedResultsController performFetch:&amp;error]) NSLog(@"Error performing fetch on fetchedResultsController: %@", [error localizedDescription]); if (fetchedResultsController == nil || [[fetchedResultsController fetchedObjects] count] == 0) { Student *student = [NSEntityDescription insertNewObjectForEntityForName:@"Student" inManagedObjectContext:[appDelegate managedObjectContext]]; NSData *classRoomStudentData = [[NSData alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"STUDENT_ATTENDANCE" ofType:@"XML"]]; [student setClassRoom:@"default"]; [student buildWithStudentData:classRoomStudentData startingWithXPathNode:@"//attendance"]; NSError *error; if (![[appDelegate managedObjectContext] save:&amp;error]) { NSLog(@"Error saving the managedObjectContext: %@", [error localizedDescription]); } if (![fetchedResultsController performFetch:&amp;error]) NSLog(@"Error performing fetch on fetchedResultsController: %@", [error localizedDescription]); } return fetchedResultsController; } </code></pre> <p>Each time I run my app the number of Student objects increases by the number of original entities (each original entity is duplicated once). So if I start with 4, the next time I get 8, then 12, then 16, etc. I can't seem to figure out why since the code to parse the XML only gets called when the fetch returns no objects.</p> <p>Any help would be appreciated, thanks.</p> <p>-- Michael</p>
 

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