No suitable mapping model found for core data migration

Question

I\'m trying to perform an iOS Core Data migration that requires a MappingModel. Core data is not able to use the mapping model for some reason and it falls back to an automa

Answer 1

In your persistentStoreCoordinator method give this line of code

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

If this doesnt help then you need to go for user implemented migration. So you will have to create a mapping model using source and destination model. In that case set,

NSDictionary *options=[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES],NSMigratePersistentStoresAutomaticallyOption,[NSNumber numberWithBool:NO],NSInferMappingModelAutomaticallyOption, nil];

Create douce metadata with following code

if (sourceMetadata) {
        NSString *configuration = nil;
        NSManagedObjectModel *destinationModel = [self.persistentStoreCoordinator managedObjectModel];

        //Our Source 1 is going to be incompatible with the Version 2 Model, our Source 2 won't be...
        BOOL pscCompatible = [destinationModel isConfiguration:configuration compatibleWithStoreMetadata:sourceMetadata];
        NSLog(@"Is the STORE data COMPATIBLE? %@", (pscCompatible==YES) ?@"YES" :@"NO");

        if (pscCompatible == NO) {
            migrationSuccess = [self performMigrationWithSourceMetadata:sourceMetadata toDestinationModel:destinationModel];
        }
    }
    else {
        NSLog(@"checkForMigration FAIL - No Source Metadata! \nERROR: %@", [error localizedDescription]);
    }

and implement the following function

- (BOOL)performMigrationWithSourceMetadata :(NSDictionary *)sourceMetadata toDestinationModel:(NSManagedObjectModel *)destinationModel
{
    BOOL migrationSuccess = NO;
    //Initialise a Migration Manager...
    NSManagedObjectModel *sourceModel = [NSManagedObjectModel mergedModelFromBundles:nil
                                                                    forStoreMetadata:sourceMetadata];
    //Perform the migration...
    if (sourceModel) {
        NSMigrationManager *standardMigrationManager = [[NSMigrationManager alloc] initWithSourceModel:sourceModel
                                                                                      destinationModel:destinationModel];
        //Retrieve the appropriate mapping model...
        NSMappingModel *mappingModel = [NSMappingModel mappingModelFromBundles:nil
                                                                forSourceModel:sourceModel
                                                              destinationModel:destinationModel];
        if (mappingModel) {
            NSError *error = nil;
            NSString *storeSourcePath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent:@"Recipes.sqlite"];
            NSURL *storeSourceUrl = [NSURL fileURLWithPath: storeSourcePath];
            NSString *storeDestPath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent:@"Recipes2.sqlite"];
            NSURL *storeDestUrl = [NSURL fileURLWithPath:storeDestPath];

            //Pass nil here because we don't want to use any of these options:
            //NSIgnorePersistentStoreVersioningOption, NSMigratePersistentStoresAutomaticallyOption, or NSInferMappingModelAutomaticallyOption
            NSDictionary *sourceStoreOptions = nil;
            NSDictionary *destinationStoreOptions = nil;

            migrationSuccess = [standardMigrationManager migrateStoreFromURL:storeSourceUrl
                                                                        type:NSSQLiteStoreType
                                                                     options:sourceStoreOptions
                                                            withMappingModel:mappingModel
                                                            toDestinationURL:storeDestUrl
                                                             destinationType:NSSQLiteStoreType
                                                          destinationOptions:destinationStoreOptions
                                                                       error:&error];
            NSLog(@"MIGRATION SUCCESSFUL? %@", (migrationSuccess==YES)?@"YES":@"NO");
        }
    }
    else {
        //TODO: Error to user...
        NSLog(@"checkForMigration FAIL - No Mapping Model found!");
        abort();
    }
    return migrationSuccess;
}