NSPredicate for one-to-many relationship

Question

Assuming a Department entity and an Employee entity with a one-many relationship
Assuming relationship called employees on Department and department on Employee
Assuming Employee has an attribute name

I need to fetch all Departments that don't have an Employee called "Bob"

Based on other answers on SO that I've read, I've tried this:

name = @"Bob";
predicate = [NSPredicate predicateWithFormat:@"ALL employees.name != %@", name];

but it doesn't seem to work. Any ideas?

Thanks.

No, here is the exact duplicate) http://stackoverflow.com/questions/1347776/how-to-correctly-setup-a-nspredicate-for-a-to-many-relationship-when-using-core — Nikita Pestrov, Sep 01 '12 at 22:12
Thanks. For the record I needed to change it to: `[NSPredicate predicateWithFormat:@(SUBQUERY(employees, $sub, $sub.name == %@).@count == 0)`, name]; — nick, Sep 02 '12 at 00:18
@dnickthomas: A SUBQUERY is not really needed here, see my answer below. — Martin R, Sep 02 '12 at 06:12

score 6 · Accepted Answer · answered Sep 02 '12 at 05:29

6

Do do not need a subquery here:

name = @"Bob";
predicate = [NSPredicate predicateWithFormat:@"NOT ANY employees.name == %@", name];

For some reason, the "ALL" aggregate does not work with to-many relationships, but the "ANY" aggregate works.

answered Sep 02 '12 at 05:29

Martin R

1 Answers1