On Jun 21, 2009, at 19:02, Jerry Krinock wrote:
It turns out that I wasn't inserting any Bars at all into that moc.
But when I did this:
[foo1 setBar:bar] ;
[foo2 setBar:bar] ;
the Foos and the bar were in different managed object contexts that
had different stores -- Yikes -- I was setting cross-store
relationships. Apparently, the Core Data runtime responds to this
attempt cordially, by "doing what I mean". It copies attributes and
inserts a new one into the same managed object context as the other
object in the relation.
This sent me searching the documentation for something that talks
about cross-context (not cross-store) relationships, but haven't yet
found anything definitive. There's an implication that different
contexts may contain different realizations of the same "store-
object" (mediated by UID, under the presumption of the same persistent
store), and half an implication that cross-context relationships might
be resolved at save time (under the same presumption about the
persistent store).
That suggests that if there are cross-context, cross-store
relationships between objects which are each realized only in a single
context/store, cross-context resolution might well realize the
"missing" object realizations first, each in the correct (because
only) store for its context, thus eliminating the cross-store
references before they can be detected.
If that's so, I would call it a bug, not "doing what I mean". So, to
summarize:
(1) What are the conditions (if any) for a cross-context relationship
to be valid?
(2) What invalid cross-context relationships are failing to be
detected by Core Data?
Seems to me both might be worth filing a bug report -- the first
against the documentation, and the second (using what could be a very
simple example you're now in a position to construct) against the
functionality.
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