Design issue for MVC and database updates

[jocked at chello.se (Joakim Danielson)]

Thank you for your reply.

Key-value observing does seem like the right way to do this. I'll give  
it a try.

Joakim

On 2004-03-03, at 00.55, Scott Stevenson wrote:

>
> On Mar 2, 2004, at 3:03 PM, Joakim Danielson wrote:
>
>> Well the problem is not in the database methods really but more what  
>> I must implement to see which object's how has changed. But I supply   
>> the method anyway:
>>
>> - (IBAction)saveToDb:(id)sender
>
> Your best bet is probably key-value observing (Panther only):
> http://developer.apple.com/documentation/Cocoa/Conceptual/ 
> KeyValueObserving/
>
> You can observe each item, and whenever the a value changes in the  
> object, you can add them item to a "changedObjects" mutable array.  
> This is probably best done outside of the NSArrayController.
>
>
> Then, you change your database saving action method to this:
>
> - (IBAction)saveToDb:(id)sender {
>
>     NSEnumerator *iterator;
>     JDTransactionType *item;
>     int newId;
>
>     // get the list of changed objects
>     NSMutableArray * changedObjects = [self changedObjects];
>     iterator = [changedObjects objectEnumerator];
>
>     ....
>
>     // after you're done, empty the array
>     [objectsToUpdate removeAllObjects];
> }
>
>
> I haven't yet found a way to ask NSArrayController which object it  
> just edited (although it seems like a something a lot of people would  
> use). But if someone else has, that would negate the need to observe  
> each object separately.
>
> I guess it would be pretty easy to override -objectDidBeginEditing to  
> check -selection and add it to an array, or something of that nature.  
> Not sure if it's reasonable to assume the selection is the one being  
> edited.
>
>     - Scott
>
> --
> Tree House Ideas
> http://treehouseideas.com/
>
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