Re: set values in coredata
Re: set values in coredata
- Subject: Re: set values in coredata
- From: Brian Todd <email@hidden>
- Date: Sat, 10 Feb 2007 21:33:33 -0800
Thank you for your patience. I read all of these documents prior to
asking my question and I wasn't clear which pieces were necessary to
simply modify a value in an instance of a managed object. I tried to
write this code and while it compiles and runs it doesn't change the
data. I stepped through this method and it is getting called so I
must be missing something obvious.
I left out the predicate and the sort descriptor because I think
they are optional. The black code I left out because I am trying to
use key-value coding to change the value and I don't know how it fits
into the picture.
NSManagedObjectContext *context = [self managedObjectContext];
NSEntityDescription *dailyValuesEntity = [NSEntityDescription
entityForName:@"DailyValue"
inManagedObjectContext:context];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:dailyValuesEntity];
[request setValue:[NSNumber numberWithInt:100] forKey:@"value"];
// left out because I am trying to use key-value coding to change the
value.
NSError *error = nil;
NSArray *array = [managedObjectContext executeFetchRequest:request
error:&error];
p.s. I will try to be more precise with my terminology. After reading
a lot of documentation all the terms start to mix in my head.
On Feb 10, 2007, at 8:00 PM, mmalc crawford wrote:
On Feb 10, 2007, at 7:44 PM, Brian Todd wrote:
When I change a value in a text field I would like all the
values in a core data entity to change based on the modified
value. I have been trying to figure out if there is a way to do
this with bindings but I haven't figured it out yet.
The Core Data documentation strongly recommends *not* trying to
learn bindings and Core Data at the same time:
<http://developer.apple.com/documentation/Cocoa/Conceptual/
CoreData/Articles/cdBeforeYouStart.html>
The reason that I have the calculated values in their own entity
instead of created when I need them is that the user can choose to
modify them individually and disable the calculation.
It is not clear what this means.
It would be helpful if you used appropriate terminology -- for
example, you should differentiate between entities and managed
objects.
If as I suspect, there is no elegant way to use bindings for
this. What is the most straightforward way to modify entity values
in coredata?
Assuming you mean, how do you change property values in an instance
of a managed object, this is covered here:
<http://developer.apple.com/documentation/Cocoa/Conceptual/
CoreData/Articles/cdUsingMOs.html#//apple_ref/doc/uid/
TP40001803-212651>
It seems like it should be just a couple lines of code but I can't
tell from Apple's docs if I need to create a fetch request and
subclass NSManagedObjectContext just to edit a value.
Nowhere does the documentation suggest subsclassing
NSManagedObjectContext.
You use a fetch request to retrieve managed objects, as described
here:
<http://developer.apple.com/documentation/Cocoa/Conceptual/
CoreData/Articles/cdFetching.html>
mmalc
Brian Todd
email@hidden
www.dancelesson.us
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