NSPredicate, get results with a subset of one-to-many relationship

Question

I\'mm working around with Core Data and NSFetchedResultsController.

My Data Model looks like this:

Product with one-to-many relat

Answer 1

What you want to achieve could be reached in two ways:

using a SUBQUERY

[NSPredicate predicateWithFormat:@"SUBQUERY(dataLines, $x, $x.theWeek == %@).@count > 0)", [NSNumber numberWithInt:18]];

or the ANY modifier

[NSPredicate predicateWithFormat:@"ANY dataLines.theWeek == %@", [NSNumber numberWithInt:18]];

You can do also the following if you need to check against multiple values:

[NSPredicate predicateWithFormat:@"SUBQUERY(dataLines, $x, $x.theWeek == %@ or $x.theWeek == %@).@count > 0)", [NSNumber numberWithInt:18], [NSNumber numberWithInt:19]];

The same can be applied to ANY modifier. ANY ... OR ANY ....

Maybe if you share some code we could help you.

P.S. I suppose you don't use scalar values and theWeek is a number.

Hope it helps.