I'm wondering if there's a straightforward was to have an
NSArrayController make a Core Data fetch for its content where the
fetch predicate can match against a parameter bound to some selection
in another control.
In my case I have a list of objects of class A in a control with
single selection, and would like another control to be populated with
Core Data items of a particular entity, where some attribute is
related to something in the selected A. The fetch predicate could of
course be something like:
attribute == A.foo
and the Entity name set to the right kind (having 'attribute' as an
attribute). However, the key 'A.foo' would need to be reachable, and
I don't think there's any binding I can make that simply gets the
selection of another control into the scope of this one so that I
could address a key path on it.
Clearly, I'm trying to be 'frugal' here. I'm aware that I can achieve
what I want by binding the content to, say, a Window Controller key
that has the appropriate logic in its get accessor to generate the
list of objects I want (from having a binding to the selection in the
'upstream' control).
I suppose my question boils down to the following:
If you want to 'restart' the master-detail chain between controls,
because there's no way to simply refer to a child (model key) of a
selection binding, do you essentially have to resort to some
'external' logic to do this?
It strikes me that if I could have a 'general' binding to the upstream
selection, then I may be able to refer to this via a key in my filter
predicate and thus start a new 'master' set of objects.
Cheers
-- Lwe
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