Core data migration failing with "Can't find model for source store" but managedObjectModel for source is present
- by Ira Cooke
I have a cocoa application using core-data, which is now at the 4th version of its managed object model.
My managed object model contains abstract entities but so far I have managed to get migration working by creating appropriate mapping models and creating my persistent store using addPersistentStoreWithType:configuration:options:error and with the NSMigratePersistentStoresAutomaticallyOption set to YES.
NSDictionary *optionsDictionary = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
NSURL *url = [NSURL fileURLWithPath: [applicationSupportFolder stringByAppendingPathComponent: @"MyApp.xml"]];
NSError *error=nil;
[theCoordinator addPersistentStoreWithType:NSXMLStoreType configuration:nil URL:url options:optionsDictionary error:&error]
This works fine when I migrate from model version 3 to 4, which is a migration that involves adding attributes to several entities. Now when I try to add a new model version (version 5), the call to addPersistentStoreWithType returns nil and the error remains empty. The migration from 4 to 5 involves adding a single attribute.
I am struggling to debug the problem and have checked all the following;
The source database is in fact at version 4 and the persistentStoreCoordinator's managed object model is at version 5.
The 4-5 mapping model as well as managed object models for versions 4 and 5 are present in the resources folder of my built application.
I've tried various model upgrade paths. Strangely I find that upgrading from an early version 3 - 5 works .. but upgrading from 4 - 5 fails.
I've tried adding a custom entity migration policy for migration of the entity whose attributes are changing ... in this case I overrode the method beginEntityMapping:manager:error: . Interestingly this method does get called when migration works (ie when I migrate from 3 to 4, or from 3 to 5 ), but it does not get called in the case that fails ( 4 to 5 ).
I'm pretty much at a loss as to where to proceed. Any ideas to help debug this problem would be much appreciated.
