Re: Binding Dependencies
Re: Binding Dependencies
- Subject: Re: Binding Dependencies
- From: Brian Webster <email@hidden>
- Date: Sun, 16 Nov 2003 12:40:07 -0600
I don't believe that the trigger will accept full key paths, only
simple keys (the docs don't say explicitly, but if key paths were
allowed, I think the method would be named setKeyPaths:... instead).
So, I think you may have to update the balance manually, by observing
the "amount" key on each transaction in the account by calling
addObserver:forKeyPath:options:context:
On Nov 16, 2003, at 11:51 AM, Jorge Ramirez wrote:
I have a question regarding the
"setKeys:triggerNotificationsForDependentKey:" method. I am creating a
very litmited accounting program while I learn about binding and the
NSController class. I have the following classes with the given
attributes...
Account Class
float openingBalance;
NSString *name;
NSMutableArray *transactions;
Transaction Class
float amount;
NSString *payee;
NSDate *date;
NSString *category;
BOOL cleared;
My question is the following, I have a "balance" method in the account
class which sums the transaction amounts using the @sum operator.
Since the balance depends on the transactions and their amounts, i
would like to use the "setKeys:triggerNotificationsForDependentKey:"
method to recalculate the balance everytime an amount is changed or a
transaction is added. I have tried putting the following in the
"+initialize" method of the account class...
[self setKeys:[NSArray arrayWithObjects:@"transactions.amount",
nil]
triggerChangeNotificationsForDependentKey:@"balance"];
but this is not working. when i change a transaction amount, the
balance does not get changed. I have also tried just "transactions"
for the key. How should i set the key for the dependency?
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--
Brian Webster
email@hidden
http://homepage.mac.com/bwebster
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