NSPredicate (Core Data fetch) to filter on an attribute value being present in a supplied set (list)
- by starbaseweb
I'm trying to create a fetch predicate that is the analog to the SQL "IN" statement, and the syntax to do so with NSPredicate escapes me.
Here's what I have so far (the relevant excerpt from my fetching routine):
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription *entity = [NSEntityDescription entityForName:
@"BodyPartCategory" inManagedObjectContext:_context];
[request setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(name IN %@)",
[RPBodyPartCategory defaultBodyPartCategoryNames]];
[request setPredicate:predicate];
The entity "BodyPartCategory" has a string attribute "name". I have a list of names (just NSString objects) in an NSArray as returned by:
[RPBodyPartCategory defaultBodyPartCategoryNames]
So let's say that array has string such as {@"Liver", @"Kidney", @"Thyroid"} ... etc.
I want to fetch all 'BodyPartCategory' instances whose name attribute matches one of the strings in the set provided (technically NSArray but I can make it an NSSet).
In SQL, this would be something like:
SELECT *
FROM BodyPartCategories
WHERE name IN ('Liver', 'Kidney', 'Thyroid')
I've gone through various portions of the Predicate Programming Guide, but I don't see this simple use case covered.
Pointers/help much appreciated!
