Core Data: How do you count records in a persistent store?
Core Data: How do you count records in a persistent store?
- Subject: Core Data: How do you count records in a persistent store?
- From: "Frederick C. Lee" <email@hidden>
- Date: Sun, 2 Apr 2006 11:16:38 -0700
This is a very simple question, yet I keep screwing it up.
How do you count (or determine empty) data from a persistent store
(table)?
I've been trying to use the '@count' qualifier to determine if I have
data
in a particular MO entity:
(gdb) po [[[[[managedObjectContext persistentStoreCoordinator]
managedObjectModel] entities] objectAtIndex:6]
valueForKey:@"name.@count"]
Program received signal SIGTRAP, Trace/breakpoint trap.
0x92902340 in _NSRaiseError ()
2006-04-02 11:12:15.092 eWorld[630] An uncaught exception was raised
2006-04-02 11:12:15.093 eWorld[630] [<NSEntityDescription 0x3826150>
valueForUndefinedKey:]: this class is not key value coding-compliant
for the key name.@count.
2006-04-02 11:12:15.094 eWorld[630] *** Uncaught exception:
<NSUnknownKeyException> [<NSEntityDescription 0x3826150>
valueForUndefinedKey:]: this class is not key value coding-compliant
for the key name.@count.
The program being debugged was signaled while in a function called
from GDB.
GDB remains in the frame where the signal was received.
To change this behavior use "set unwindonsignal on"
Evaluation of the expression containing the function (objc_msgSend)
will be abandoned.
(gdb)
Regards,
Ric.
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