Re: NSUndoManager messing up Core Data database
Re: NSUndoManager messing up Core Data database
- Subject: Re: NSUndoManager messing up Core Data database
- From: Ruotger Skupin <email@hidden>
- Date: Thu, 9 Oct 2008 12:21:17 +0200
Hi Ron,
I wasn't clear enough on one point. The main thread context's undo
manager crashes (the posted backtrace), but changing the DB only
happens in the background thread. Assuming no binding changes the main
thread context, there shouldn't be anything to undo in the main thread
context. I cannot be 100% sure the bindings behave read-only when they
should, of course.
btw.: I'd like to propose that there should be a way to switch a
context to read-only. I'd file a radar if you want me to.
Am 08.10.2008 um 18:23 schrieb Ron Lue-Sang:
The background thread (called database access thread) is the one
that changes the database exclusively, all database modifying is
funnelled through it. The main thread is supposed to only read-
access the database. How do I do that? Since I already use
mogenerator (http://rentzsch.com/code/mogenerator) I changed the
generator template to check for the correct thread on write access.
That way I could pinpoint a lot of accidental write accesses, which
led to context inconsistencies.
There's one I could not get rid of. It is done by the
NSUndoManager. Which is weird as there is no write access to the
database from the main thread the NSUndoManager is so keen on
undoing. What is going on?
In my case I'd like to get rid of the NSUndoManager altogether as I
don't need it. Is there a way to do that?
Well, the short answer is:
backgroundManagedObjectContext = [[NSManagedObjectContext alloc]
init];
[backgroundManagedObjectContext setUndoManager:nil];
But that's assuming that the undoManager in frame 15 of your bt is
[backgroundManagedObjectContext undoManager]. I think that's the
only way you'd get into the situation you've described.
--------------------------
RONZILLA
Ruotger
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