Re: Core Data, bindings & to-many relationship
Re: Core Data, bindings & to-many relationship
- Subject: Re: Core Data, bindings & to-many relationship
- From: Wain <email@hidden>
- Date: Tue, 13 Dec 2005 23:13:45 +0000
Hi,
It sounds like you have two controllers, both bound to the managed
object context
and both finding all of the appropriate entity's (Trip and
Transaction respectively).
What it sounds like you actually want is one controller bound to the
managed
object context for Trip entities, and a second controller bound to
the selection
of the first controller, rather than the managed object context.
This binding should probably be made to the "contentSet" binding of
the second controller,
bind to the first controller with a model key path something like
"selection.transactions".
I thought this was in the apple bindings docs but I can't find it
quickly (so I'm probably wrong)...
this:
http://cocoadevcentral.com/articles/000080.php will do nicely
though.
(check out the setup of the mailboxes array controller about half way
down the article).
Wain
On 13 Dec 2005, at 22:51, Paul Gribble wrote:
I am writing a little toy app using Core Data to keep track of my
expenses
when I travel. I have a "Trip" entity with attributes like dateStart,
dateEnd, location, purpose, etc. I have the interface for this
working, of
course it's not that difficult.
What I want to do next is have a list of "transactions" for each
trip that
keep track of money spent. Each transaction would have a date,
amount, and
purpose.
I have tried creating a "Transaction" entity in the data model, and
connecting the "Trip" entity to it using a to-many relationship,
and the
inverse connection back to "Trip" using a to-one relationship.
The problem I am running into now is that in my GUI I can see a
list of ALL
transactions for all trips, but how do I make my NSListView only
display
transactions for the currently selected Trip?
I have read all of the Apple tutorials on core data and bindings
and I am
still at a loss.
Thanks for any suggestions,
PS I also thought of doing the following: write a custom "Trip"
class that
has as one of its instance variables an NSArray that would then
contain my
"transactions" for the particular trip. This would sidestep core data
however and I thought, there must be a way to do this using core data.
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