Smart Containers

[Christiaan Hofman]

I am totally confused about your store setup. Do you have 3 persistent
store, and why would you want that? Usually you have one persistent store
for each URL. You have at least 2 (the default one, and the documentStore
you added, I don't know what unsavedDocumentStore is). There might be a
problem that some group is on one persistent store, while the containing
objects it refers to is in another.

Christiaan

On 2/6/07, Stefan Urbanek <stefan at agentfarms.net> wrote:
>
>
> On 15.1.2007, at 17:16, Christiaan Hofman wrote:
>
> > I suggest you try to work through the CoreRecipes example project(s),
> > it contains smart groups and a UI to create predicates for smart
> > groups (be careful because it contains some bugs, at least the last
> > time I looked at it.)  It's fairly complex, but that's just the way
> > it is (though I think their UI controller is a bit too complicated.)
> > This should give you an idea of the concepts involved in building
> > smart groups. If you have questions about specific (implementation)
> > details, you can come back to this list with those.
> >
>
> Thank you for your suggestion. I am now following the CoreRecipes
> example, with small modifications - I use NSPersistentDocument. I
> will try to create a short how-to to this problem after finishing it :-)
>
> The basic model is similar to the CoreRecipes:
>
> Group -> Context
> SmartGroup -> AbstractContext (i will use 'smart folder' name here)
> ManualGroup -> ConcreteContext (i will use 'folder' name here)
> Recipe -> Object
>
> initialisation of document:
> - set up a persistent store for 'smart folder'
> - set up smart folder called Universe and assign it to the 'smart' store
> - create 'unsaved document store'
>
> in configurePersistentStoreCoordinatorForURL I do:
>
>      if unsavedDocumentStore != nil
>
>          documentStore = [coordinator
> migratePersistentStore:unsavedDocumentStore
>                                                        toURL:url
>                                                      options:nil
>
> withType:NSXMLStoreType
>                                                        error:error];
>
>      else
>
>          documentStore = [coordinator
> addPersistentStoreWithType:NSXMLStoreType
>                                                    configuration:nil
>                                                              URL:url
>                                                          options:nil
>                                                            error:error];
>
> I have special action method for creating new concrete folder,
> similar to one in CoreRecipes. This is to make sure that the new
> folder is placed to the document persistent store. Also to prevent
> array controller to create instance of an abstract class.
>
> The UI is quickly designed as follows:
> - table view for folders
> - table view for objects
> - some text fields for selected object
> - array controller for folders
> - array controller for objects
>
> Folder creation works, object creation works as well. The 'Universe'
> folder works as expected. When I save the document without objects,
> only with new folders, it works. When I create some objects and try
> to save the document I get:
>
> 2007-02-06 00:10:55.048 SocNet6[6838] *** -[NSCFArray
> subarrayWithRange:]: index (2) beyond bounds (2)
>
> Stack:
>
> #0      0x9297c008 in -[NSException raise]
> #1      0x9297be5c in +[NSException raise:format:]
> #2      0x92985248 in -[NSArray subarrayWithRange:]
> #3      0x940ceb08 in -[NSPersistentStoreCoordinator(_NSInternalMethods)
> executeRequest:withContext:]
> #4      0x940e1b68 in -[NSManagedObjectContext save:]
> #5      0x93c39ee4 in -[NSPersistentDocument
> writeToURL:ofType:forSaveOperation:originalContentsURL:error:]
> #6      0x93953458 in -[NSDocument
> _writeToURL:ofType:forSaveOperation:inFolder:makingTemporaryCopyInFolder
> :error:]
> #7      0x93952f6c in -[NSDocument
> _writeSafelyToURL:ofType:forSaveOperation:error:]
> #8      0x93952cc8 in -[NSDocument
> writeSafelyToURL:ofType:forSaveOperation:error:]
> #9      0x93c3a1fc in -[NSPersistentDocument
> writeSafelyToURL:ofType:forSaveOperation:error:]
> #10     0x93952a08 in -[NSDocument
> saveToURL:ofType:forSaveOperation:error:]
> #11     0x93a3fce8 in -[NSDocument
> _saveToURL:ofType:forSaveOperation:delegate:didSaveSelector:contextInfo:
> ]
> #12     0x93952944 in -[NSDocument
> saveToURL:ofType:forSaveOperation:delegate:didSaveSelector:contextInfo:]
> #13     0x939526c4 in -[NSDocument
> saveDocumentWithDelegate:didSaveSelector:contextInfo:]
> #14     0x937acc4c in -[NSApplication sendAction:to:from:]
> ...
>
> I do not know what the array is. The number 2 does not reflect
> anything known to me - neither number of objects, nor number of
> folders. Only known 2 is number of persistent stores.
>
> Does anyone know what is possibly causing the problem? What should I
> try to get more information about what is going on?
>
> Thanks for any hints,
>
> <rest snipped>
>
> Stefan Urbanek
> --
> http://stefan.agentfarms.net
>
> First they ignore you, then they laugh at you, then they fight you,
> then you win.
> - Mahatma Gandhi
>
>
>
>