Re: Core Data, bindings & to-many relationship
Re: Core Data, bindings & to-many relationship
- Subject: Re: Core Data, bindings & to-many relationship
- From: "Paul L. Gribble" <email@hidden>
- Date: Wed, 14 Dec 2005 11:22:18 -0500
- Thread-topic: Core Data, bindings & to-many relationship
Wain: Thanks - that's exactly what I needed!
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>
Hi,
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>
It sounds like you have two controllers, both bound to the managed
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object context
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and both finding all of the appropriate entity's (Trip and
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Transaction respectively).
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>
What it sounds like you actually want is one controller bound to the
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managed
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object context for Trip entities, and a second controller bound to
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the selection
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of the first controller, rather than the managed object context.
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This binding should probably be made to the "contentSet" binding of
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the second controller,
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bind to the first controller with a model key path something like
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"selection.transactions".
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>
I thought this was in the apple bindings docs but I can't find it
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quickly (so I'm probably wrong)...
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>
this: http://cocoadevcentral.com/articles/000080.php will do nicely
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though.
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(check out the setup of the mailboxes array controller about half way
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down the article).
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>
Wain
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>
On 13 Dec 2005, at 22:51, Paul Gribble wrote:
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> I am writing a little toy app using Core Data to keep track of my
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> expenses
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> when I travel. I have a "Trip" entity with attributes like dateStart,
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> dateEnd, location, purpose, etc. I have the interface for this
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> working, of
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> course it's not that difficult.
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>
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> What I want to do next is have a list of "transactions" for each
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> trip that
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> keep track of money spent. Each transaction would have a date,
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> amount, and
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> purpose.
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>
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> I have tried creating a "Transaction" entity in the data model, and
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> connecting the "Trip" entity to it using a to-many relationship,
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> and the
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> inverse connection back to "Trip" using a to-one relationship.
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>
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> The problem I am running into now is that in my GUI I can see a
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> list of ALL
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> transactions for all trips, but how do I make my NSListView only
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> display
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> transactions for the currently selected Trip?
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>
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> I have read all of the Apple tutorials on core data and bindings
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> and I am
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> still at a loss.
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>
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> Thanks for any suggestions,
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>
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> PS I also thought of doing the following: write a custom "Trip"
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> class that
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> has as one of its instance variables an NSArray that would then
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> contain my
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> "transactions" for the particular trip. This would sidestep core data
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> however and I thought, there must be a way to do this using core data.
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