NSPredicate core data, fetch some objects

Question

I have an entity, ProductCart & Cart, with a to many relationship. ProductCart has an attribute called ordered, which determine if the product has been ordered. Now I want to fetch all the objects in ProductCart which has'nt been ordered. Have tried something like this but it does not work:

NSFetchRequest *fetchRequest =  [NSFetchRequest fetchRequestWithEntityName:@"ProductCart"];
fetchRequest.predicate = [NSPredicate predicateWithFormat:@"inCart == %@ && !ordered == %@", cart, [self valueForKey:@"ordered"]];

NSSortDescriptor *sortDescriptor =  [[NSSortDescriptor alloc] initWithKey:@"products.name" ascending:YES];
NSArray *sortDescriptors = @[sortDescriptor];
[fetchRequest setSortDescriptors:sortDescriptors];

inCart fetches the relationship, ordered is giving me problems. How can I fix this?

Answer 1

I expect your predicate should be more like:

fetchRequest.predicate = [NSPredicate predicateWithFormat:@"inCart == %@ && ordered == NO", cart];

because you just want to test the state of ordered rather than trying to compare it to some other value.