CODEWITHSUNDEEP
ioscore-datansfetchedresultscontrollernspredicate
larjudge
larjudge

Reputation: 2163

Issue with NSPredicate in fetchedResultsController method

I'm creating an app that lets a salesperson order stock for their customers from their iPhone.

The user navigates to a customer and creates an order. A blank tableview appears and the user then adds items to the tableview by selecting them from an inventory screen.

When they add an item to the order, the navigation controller pops the view and shows the order view again. The user should only be able to see orders for that customer.

I originally built the app entirely in sqlite and I achieved this by using the query 

SELECT PRODUCT FROM TRANSLINE WHERE CUSTOMERACCNO = ?

I have now moved onto Core Data and I need to achieve the same functionality. I'm trying to implement this behaviour in the fetchedResultsController method using NSPredicate, but I can't seem to get it working - all I get is a blank screen. However, when I don't implement it, I get ALL orders i.e. orders for every customer, not just this one.

Here's my code :

- (NSFetchedResultsController *)fetchedResultsController
{
    if (__fetchedResultsController != nil) {
        return __fetchedResultsController;
    }

    // Create the fetch request for the entity.
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Configure the Entity
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"TransLine" inManagedObjectContext:__managedObjectContext];
    [fetchRequest setEntity:entity];

    [fetchRequest setFetchBatchSize:20];

    //Configure the predicate
    [NSFetchedResultsController deleteCacheWithName:@"Root"];  
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"customerAccountNo == %@", _customerAccountNo];
    [fetchRequest setPredicate:predicate];

    //Configure Sort Descriptors
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"PRODAC" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
    [fetchRequest setSortDescriptors:sortDescriptors];


    // nil for section name key path means "no sections".
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:__managedObjectContext sectionNameKeyPath:nil cacheName:@"Root"];
    aFetchedResultsController.delegate = self;

    self.fetchedResultsController = aFetchedResultsController;

    [aFetchedResultsController release];
    [fetchRequest release];
    [sortDescriptor release];
    [sortDescriptors release];

    return __fetchedResultsController;
}

Thanks in advance for all your help.

Upvotes: 1

Views: 355

Answers (1)

larjudge
larjudge

Reputation: 2163

Well, it seems that in my frustration.... I am, in fact, an idiot. Guess what I forgot to include.

    NSError *error = nil;
    if (![self.fetchedResultsController performFetch:&error])
    {
      NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

Upvotes: 1

Related Questions