Core Data and Predicate

Question

Say I have an Entity Department that has a to-many relationship with Persons. I want to be able to search the Department Sports to see if Person Scott Olsen works there. The Person Scott Olsen is not unique (there may be 3 Scotts working in 3 different Departments).

How can I search the Department Sports to find the Person Scott Olsen that works there and not find the other Scotts?

The basic way I can think of is:

for (Person *person in sports.persons) {
    if ([person.name isEqualToString:@"Scott Olsen"]) {
        // found him!
    }
}

Or:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY persons.name == 'Scott Olsen'"];

Department *department = [Department MR_findFirstWithPredicate:predicate];

But I'm unsure if the second returns the Scott Olsen that works in Departement Sports. I suppose I could then check

if ([department.name isEqualToString:@"Sports"])

But it seems like there should be a better way to do it with a NSPredicate, but I can't figure it out.

Answer 1

Is this what you are looking for?

NSString *name = @"Scott Olsen";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name = %@", name];
NSSet *filtered = [sports.persons filteredSetUsingPredicate:predicate];

Or (your question changed after I posted the above code):

NSString *name = @"Scott Olsen";
NSString *department = @"Sports";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name = %@ AND department = %@",
      name, department];
Person *person = [Person MR_findFirstWithPredicate:predicate];

(assuming that you have an inverse relationship "department" from Person to Department).

Answer 2

Just add second expression in your predicate:

[NSPredicate predicateWithFormat:@"name == 'Sports' && ANY persons.name == 'Scott Olsen'"];