On Dec 30, 2009, at 10:12, Brad Gibbs wrote:
> Account <--->>ProjectSite<--->>Project
>
> I'm trying to get the projects array controller to load all projects for the
> selected Account (so, all Projects for all ProjectSites).
>
> I've got an NSTableView listing accounts on the left, and view controllers to
> display detail table views to the right. One of the detail table views lists
> all ProjectSites for the selected Account. That's working fine. Another
> detail table view should list all Projects for the Account, but I can't get
> the Projects array controller to bind to the selected Account. These methods
> list all projects for the selected Account:
>
> NSLog(@"Projects for account are %@", [self.selections.account
> valueForKeyPath:@"projectSites.projects.displayName"]);
> NSLog(@"All projects for account are %@", [[self.selections.account
> allProjectsForAccount] valueForKey:@"displayName"]);
>
> But, I can't translate that into the proper ContentSet binding for the
> Projects AC. I've tried every combination I could think of, including:
>
> 1. creating an Object Controller for the selectedAccount and binding the
> Project's ContentSet to that controller with projectSites.projects
> 2. creating an Array Controller for the selectedAccount's ProjectSites and
> binding to that
> 3. creating a managedObject subclass for Project with a method that returns
> [self valueForKeyPath:@"projectSites.projects"] and binding the projects AC's
> contentSet to that property
> 4. using combinations of @distinctUnionOfSets
Basically, there are two usual ways you use an array controller:
1. In "entity" mode, where its "contentSet" binding is bound to a Core Data
(set) property of a data model object. It's going to use *all* the objects of
the configured Core Data entity, unless you use a filter predicate or a fetch
predicate, or unless you actually use a transient property that you've coded to
fetch only some of the objects.
You *could* use this for your projects list, but you'd have to write code to
maintain a suitable filter predicate or fetch predicate or transient property,
based on the selected account.
2. In "class" mode with a source array, where its "contentArray" binding is
bound to a non-Core Data (array) property of a data model object. It's up to
you to maintain that data model array property KVO-compliantly, or the binding
won't update reliably.
See:
http://developer.apple.com/mac/library/documentation/Cocoa/Reference/CocoaBindingsRef/BindingsText/NSArrayController.html
So I think you'll need to:
-- bind accountsArrayController's "contentSet" binding to your data model
object's "accounts" property
-- bind projectSitesArrayController's "contentArray" binding to
"accountsArrayController.selection.projectSites"
-- bind projectsArrayController's "contentArray" binding to
"projectsitesarraycontroller.arrangedobjects.projec...@distinctunionofarrays"
(because you said all projects for the account, not all projects for the
selected sites)
With these bindings (if I've got them right), only the first array controller
is in "entity" mode. So, you cannot use projectSitesArrayController or
projectsArrayController to create or delete objects directly. If you have "+"
and "-" buttons for them your interface, their action methods need to be in
(say) your document or window controller class, and you have to write code to
create suitable objects and relationships.
Your references, above, to "selections" and "allProjectsForAccount" methods
suggest that you've been trying to solve the problem by adding custom
properties to your NSManagedObject custom subclasses. The problem *is* solvable
that way, but you have to be careful to distinguish non-Core Data custom
properties, which are arrays, from Core Data "custom" (i.e. transient)
properties, which are sets. And, you have to make sure you get KVO-compliance
right -- not always easy. And, when you're using Core Data you have to be
careful that you don't mess up undo using non-Core Data custom properties.
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