Re: Help with relationship objects

2011-06-29 Thread Brad Stone 
Quincey, that helps.  Thanks

On Jun 28, 2011, at 1:36 PM, Quincey Morris wrote:

 On Jun 28, 2011, at 08:40, Brad Stone wrote:
 
 I get the below.  Notice the new SRTodoEntity is properly in the todos 
 relationship but there's also a reference to it outside of the SRNoteEntity. 
  Intuitively, I would think there should be only one reference to it inside 
 SRNoteEntity.This is my confusion.  Why is it reference twice?  How can 
 I prevent that from happening if this isn't normal?
 
 po [[self managedObjectContext] registeredObjects]
 {(
 Note uid:330961758011065
  creationDate:2009-09-05 13:21:54 -0400
  modificationDate:2009-09-06 12:41:02 -0400
  todos:Relationship objects for {(
  SRTodoEntity: 0x200483d80 (entity: SRTodoEntity; id: 0x2004121e0 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRTodoEntity/p1 ; data: {
  note = 0x2002c4e60 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRNoteEntity/p1;
  todoViewData = nil;
  })
  )} on 0x200448360
 noteData:538
 
 SRTodoEntity: 0x200483d80 (entity: SRTodoEntity; id: 0x2004121e0 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRTodoEntity/p1 ; data: {
  note = 0x2002c4e60 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRNoteEntity/p1;
  todoViewData = nil;
 })
 )}
 
 You've kinda got hold of the wrong end of this. Core Data is an object graph, 
 certainly, and any pointer to a managed object is a reference to the 
 object. There are references to these objects all over your code -- every 
 stack variable pointer is a reference. In the above example, a reference to 
 the Todo object exists inside the set of references that represents Note's 
 relationship to its Todo's. That makes it a really important reference, but 
 it's certainly never the only one.
 
 By sending a 'registeredObjects' message to the managedObjectContext (which 
 is *not* an object in the object graph), you've asked it to construct a 
 collection (a set, as it happens) of references to Core Data objects it knows 
 about. There's no *relationship* from the MOC to the managed objects, it's 
 just the MOC's job to know what managed objects are currently in memory.
 
 

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Help with relationship objects

2011-06-28 Thread Brad Stone 
I need a little guidance.  Did I properly add a relationship object?  I don't 
know what's normal in this scenario.

I referred to here: 
http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdUsingMOs.html

I have an entity called SRNoteEntity which has a to-many relationship with 
SRTodoEntity in a mutableSet called todos.  When I do the following:

[thisNote addTodosObject:todoItem];

I get the below.  Notice the new SRTodoEntity is properly in the todos 
relationship but there's also a reference to it outside of the SRNoteEntity.  
Intuitively, I would think there should be only one reference to it inside 
SRNoteEntity.This is my confusion.  Why is it reference twice?  How can I 
prevent that from happening if this isn't normal?

po [[self managedObjectContext] registeredObjects]
{(
 Note uid:330961758011065
creationDate:2009-09-05 13:21:54 -0400
modificationDate:2009-09-06 12:41:02 -0400
todos:Relationship objects for {(
SRTodoEntity: 0x200483d80 (entity: SRTodoEntity; id: 0x2004121e0 
x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRTodoEntity/p1 ; data: {
note = 0x2002c4e60 
x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRNoteEntity/p1;
todoViewData = nil;
})
)} on 0x200448360
 noteData:538

 SRTodoEntity: 0x200483d80 (entity: SRTodoEntity; id: 0x2004121e0 
x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRTodoEntity/p1 ; data: {
note = 0x2002c4e60 
x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRNoteEntity/p1;
todoViewData = nil;
})
)}

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Re: Help with relationship objects

2011-06-28 Thread Quincey Morris 
On Jun 28, 2011, at 08:40, Brad Stone wrote:

 I get the below.  Notice the new SRTodoEntity is properly in the todos 
 relationship but there's also a reference to it outside of the SRNoteEntity.  
 Intuitively, I would think there should be only one reference to it inside 
 SRNoteEntity.This is my confusion.  Why is it reference twice?  How can I 
 prevent that from happening if this isn't normal?
 
 po [[self managedObjectContext] registeredObjects]
 {(
 Note uid:330961758011065
   creationDate:2009-09-05 13:21:54 -0400
   modificationDate:2009-09-06 12:41:02 -0400
   todos:Relationship objects for {(
   SRTodoEntity: 0x200483d80 (entity: SRTodoEntity; id: 0x2004121e0 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRTodoEntity/p1 ; data: {
   note = 0x2002c4e60 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRNoteEntity/p1;
   todoViewData = nil;
   })
   )} on 0x200448360
 noteData:538
 
 SRTodoEntity: 0x200483d80 (entity: SRTodoEntity; id: 0x2004121e0 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRTodoEntity/p1 ; data: {
   note = 0x2002c4e60 
 x-coredata://614245CF-F03E-4F43-9D7F-98CDCB2899FA/SRNoteEntity/p1;
   todoViewData = nil;
 })
 )}

You've kinda got hold of the wrong end of this. Core Data is an object graph, 
certainly, and any pointer to a managed object is a reference to the object. 
There are references to these objects all over your code -- every stack 
variable pointer is a reference. In the above example, a reference to the Todo 
object exists inside the set of references that represents Note's relationship 
to its Todo's. That makes it a really important reference, but it's certainly 
never the only one.

By sending a 'registeredObjects' message to the managedObjectContext (which is 
*not* an object in the object graph), you've asked it to construct a collection 
(a set, as it happens) of references to Core Data objects it knows about. 
There's no *relationship* from the MOC to the managed objects, it's just the 
MOC's job to know what managed objects are currently in memory.


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