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Re: core data, refreshObject, multiple threads
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Re: core data, refreshObject, multiple threads


  • Subject: Re: core data, refreshObject, multiple threads
  • From: John Clayton <email@hidden>
  • Date: Sun, 07 Dec 2008 14:45:34 +0100

Chris,

Can you make use of the - (void)refreshObject:(NSManagedObject *)object mergeChanges:(BOOL)flag method on NSManagedObjectContext?

Thanks
--
John Clayton
Skype: johncclayton




On 7/12/2008, at 12:22 PM, Chris Idou wrote:

I've got fairly modest requirements, in so far as I'm using the XML store, and I'm happy to refresh the entire object graph of my worker thread when there is a change. So I've even tried [managedObjectContext reset] and querying from the beginning, but that doesn't seem to work either.

I'm starting to think in terms of rebuilding the entire PersistentStoreCoordinator / ManagedObjectContext stack as a way to get new data. But a question I've had in the back of my mind for some time now, is there is no obvious way to close a NSPersistentStoreCoordinator or close a NSManagedObjectContext. Does one simply dealloc them, or in the case of garbage collection, just throw them away? Usually database type interfaces require some kind of close API


--- On Fri, 5/12/08, Steve Steinitz <email@hidden> wrote:


From: Steve Steinitz <email@hidden>
Subject: Re: core data, refreshObject, multiple threads
To: email@hidden
Cc: email@hidden
Received: Friday, 5 December, 2008, 4:04 PM
Hi Chris,

On 5/12/08, Chris Idou <email@hidden> wrote:

I've got a main thread that handles a gui, and a
worker thread with its own persistentStoreCoordinator and
managedObjectContext. The gui notifies the worker thread of
a change, passing it an objectID, and the worker thread gets
the object, and other objects it is connected to, and calls
[managedObjectContext refreshObject: on them.

But they don't seem to get an updated object.
I'm using the XML store. The store is saved, I've
checked that the new values are in the XML. But refresh
doesn't seem to update anything. Is there any trick to
it?

Yes, I believe there are some tricks and also possibly some
cases where it just won't update anything.  Ben Trumbull
was kind enough to contribute to a similar question I posted
back in October.  Here is the thread:
http://www.mail-archive.com/email@hidden/msg19221.html

In particular see his comment about the issue with small
staleness intervals.  At the time, I thought that had solved
my problem but I've since discovered other scenarios
where refreshObject doesn't update anything.  Its
possibly more likely to occur after optimistic locking
errors (which, so far, I am unable to avoid).  But I
haven't yet demonstrated that with any degree of
scientific method.  I'm going to put it under the
microscope again over the Christmas holidays.  Feel free to
stay in touch about it.

Best regards and best of luck,

Steve


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