I've finally got the hang of NSPredicateEditor and custom
NSPredicateEditorRowTemplates. (It sure took a while and many, many
searches and head-scratchings). However, I am stuck on one thing and I
suspect that the problem might lie in the NSPredicateEditor code
itself; hence this post.
Here is what I am trying to do:
I have a Core Data document-based application for managing Tasks (to-
do items). I am using NSPredicateEditor to manage a set of user-
defined Smart Groups. I want the user to be able to build a predicate
based on a choice from a popup button. For example the (sub-)predicate
might look like this:
status == "Not Started"
Implementing this is straightforward enough, but I the wrinkle is that
want the right hand side of the expression to come from a core data
entity. So, no problem, when I create the NSPopUpButton (in my custom
NSPredicateEditorRowTemplate class) I simply fill the menuitems from
the appropriate array controller, which in turn gets its data from the
Core Data entity. After much learning and experimenting, this now
works. All is well.
So, then I realize that if (in another window) the user edits the Core
Data entity in question, the changes are not reflected in the
NSPredicateEditor popup. Okay, this seems like a candidate for cocoa
bindings. Again, after much searching and experimentation I come up
the following:
NSPopUpButton *rightPopUp = [[NSPopUpButton alloc]
initWithFrame:NSZeroRect pullsDown:NO];
[rightPopUp bind:@"content" toObject:arrayController
withKeyPath:@"arrangedObjects" options:nil];
[rightPopUp bind:@"contentValues" toObject:arrayController
withKeyPath:[NSString stringWithFormat:@"%...@.%@", @"arrangedObjects",
[self controllerKeyPath]] options:nil];
where:
- arrayController is the array controller backed by the Core Data entity
- controllerKeyPath is an NSString which holds the keypath for the
name of the NSManagedObject (ex. "name")
This works fine in that it fills the NSPopUpButton initially. It even
works across the copying that NSPredicateEditor seems to need to make.
However, if I change the underlying entity in another window (which
uses a different, but identically set up, array controller) the
NSPopUpButton menu items do not change. If I close the Smart Groups
window and start everything (NSPredicateEditor creation, etc.) all
over again, it will pick up the changes in the entity.
Just to make sure that I'm not completely nuts, I put an independent
NSPopUpButton elsewhere on the Smart Groups window and bound it (using
IB) identically to the NSPopUpButton in the row template. This popup
works perfectly: it updates the popup items in real time as expected.
I also checked that all the bindings (IB and programatically) are
actually being created by using -infoForBinding:NSContentBinding and -
infoForBinding:NSContentValuesBinding. Everything appears to be wired
up correctly.
I wonder if NSPredicateEditor is somehow blocking the change
notifications from the array controller?
Does anyone have any experience trying to bind an NSPopUpButton in a
custom NSPredicateEditorRowTemplate?
Oh, in case it matters, I am compiling for GC only.
Thanks for any advice.
Martin
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