iPhone Core Data "Automatic Lightweight Migration"

Question

I am attempting to update an app that implements a core data store. I am adding an attribute to one of the entities.

I added the following code to my delegate class:

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {

    if (persistentStoreCoordinator != nil) {
        return persistentStoreCoordinator;
    }

    NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"Shoppee.sqlite"]];

    NSError *error = nil;
    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];

    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
           [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
           [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];

    if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:options error:&error]) {
     NSLog(@"Error: %@",error);
     NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
     abort();
    }    

    return persistentStoreCoordinator;
}

This was from the following URL: Doc

I get the following error when executing the code:

2009-12-01 20:04:22.877

Shoppee[25633:207] Error: Error

Domain=NSCocoaErrorDomain Code=134130

UserInfo=0x1624d20 "Operation could not be completed. (Cocoa error 134130.)" 2009-12-01 20:04:22.879 Shoppee[25633:207] Unresolved error Error Domain=NSCocoaErrorDomain Code=134130 UserInfo=0x1624d20 "Operation could not be completed. (Cocoa error 134130.)", { URL = file://localhost/Users/Eric/Library/Application%20Support/iPhone%20Simulator/User/Applications/A8A8FB73-9AB9-4EB7-8F83-82F5B4467AF1/Documents/MyApp.sqlite; metadata = { NSPersistenceFrameworkVersion = 241; NSStoreModelVersionHashes = { Item = <869d4b20 088e5c44 5c345006 87d245cd 67ab9bc4 14cadf45 180251e9 f741a98f>; Store = <47c250f4 895e6fd1 5033ab42 22d2d493 7819ba75 3c0acffc 2dc54515 8deeed7a>; }; NSStoreModelVersionHashesVersion = 3; NSStoreModelVersionIdentifiers = ( ); NSStoreType = SQLite; NSStoreUUID = "8DC65301-3BC5-42BE-80B8-E44577B8F8E1"; }; reason = "Can't find model for source store"; }

It looks like I somehow need to include the original data model but I am not sure how to do that. Any suggestions?

Answer 1

I figured it out.

Design > Data Model > Add Model Version

Answer 2

Just a note for those that come across this Googling, it seems even with auto(magic) migration you still need to create a version of your original store, and a new one, and set the new one as the current version.

Answer 3

Also for googlers.. Simple rule, never delete/edit any old numbered version. When you Add Model Version the number suffix will increase as 2..3..4 meaning 2 is the oldest 3 next etc.. but the Current one to edit is the unnumbered version.

Do not delete old model versions as users with previous db in that model version will not be able to migrate to the latest with out comparing old and latest schemas.

Answer 4

For Googlers again, this is what you need to do (assuming you have already set up Lightweight Migration):

1. Before making changes, Do Design -> Data Model -> Add Model Version (you will see that a new .xcdatamodel is created in your .xcdatamodeld folder)
2. Save
3. Make your change
4. Save
5. Run App

Step #1 is crucial for making this work. I ran into this problem because I had followed these steps to add a new field. That worked. I added a second new field, but forgot to "Add Model Version", and things blew up.