OK, thanks again for the tips; SUBQUERY works fine. I'm actually
querying for a collection of attribute matches, which translates to a
range of SUBQUERYs in a compound predicate.
Of course, when you drill into the docs on NSExpression, there's some
pretty nice discussion on SUBQUERY, but it might be nice to lift some
of this material to the Predicate Programming Guide at some point - it
had been a while since I dabbed in Core Data queries, and I had
forgotten that there's a lot more than meets the eye in the Guide
(last time around I had discovered the power of the 10.5+ function
expression which is also pretty much a no-show in the Guide).
Another option is to invert the query: fetch all the destination
objects which meet your criteria for the destination, set the
request to prefetch the relationship you're actually interested in,
then do a second fetch with (targetObjects IN
[EMAIL PROTECTED]) and
includesPropertyValues set to NO (the data is already in the row
cache at this point).
Yes, I had tried an inverted query approach, but dealing with the
distinct unions seemed decidedly awkward to code, particularly given
the fact that I'm testing for the presence of multiple matching
attributes per projected object.
Anyway, I'm back on the right side of the tracks with Core Data, and
can start enjoying it again :-)
-- lwe
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