Don't nil Core Data inverse relationship

Question

I'm modeling a relationship in Core Data where an object Foo can have multiple Item's and an Item cannot exist without a Foo.

In the Core Data model, I have object Foo which has an optional to-many relationship named "items" to object Item where the delete rule is to cascade. Each Item has a non-optional inverse relationship back to Foo named "foo" where the count = 1 and the delete rule is set to nullify.

Currently,

foo.items = newItems;

results in the inverse relationship to Foo being nil'd for each of the old items. Is there a way to setup Core Data to preserve the inverse relationship on the old items (so they still point back to foo)?

So, you want foo.items to contain all of the old values in items plus all of the new ones in newItems? — Tom Harrington

Idles Idles · Accepted Answer · 2013-06-19T18:42:26

Why would you want to do that? It seems that since you're assigning a new set of Items (who will begin referring to the Foo), the old items should no longer refer to the Foo?

Don't nil Core Data inverse relationship

1 Answers