I keep on getting "save operation failure" after any change on my Xcode Data Model

core-data, iphone, mapping-model, version-control, xcode

Solution

Do you have NSMigratePersistentStoresAutomaticallyOption and NSInferMappingModelAutomaticallyOption options set when you create your persistentStoreCoordinator in the App Delegate?

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {

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

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

    NSError *error = nil;
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                             [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];
    if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:options error:&error]) {
        // Handle error
    }    

    return persistentStoreCoordinator;
}

Problem

I started using Core Data for iPhone development. I started out by creating a very simple entity (called Evaluation) with just one string property (called evaluationTopic). I had following code for inserting a fresh string: ``` - (void)insertNewObject { // Create a new instance of the entity managed by the fetched results controller. NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; NSEntityDescription *entity = [[fetchedResultsController fetchRequest] entity]; NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context]; // If appropriate, configure the new managed object. [newManagedObject setValue:@"My Repeating String" forKey:@"evaluationTopic"]; // Save the context. NSError *error; if (![context save:&error]) { // Handle the error... } [self.tableView reloadData]; } ``` This worked perfectly fine and by pushing the +button a new "My Repeating String" would be added to the table view and be in persistent store. I then pressed "Design -> Add Model Version" in Xcode. I added three entities to the existing entity and also added new properties to the existing "Evaluation" entity. Then, I created new files off the entities by pressing "File -> New File -> Managed Object Classes" and created a new .h and .m file for my four entities, including the "Evaluation" entity with Evaluation.h and Evaluation.m. Now I changed the model version by setting "Design -> Data Model -> Set Current Version". After having done all this, I changed my insertMethod: ``` - (void)insertNewObject { // Create a new instance of the entity managed by the fetched results controller. NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; NSEntityDescription *entity = [[fetchedResultsController fetchRequest] entity]; Evaluation *evaluation = (Evaluation *) [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context]; // If appropriate, configure the new managed object. [evaluation setValue:@"My even new string" forKey:@"evaluationSpeechTopic"]; // Save the context. NSError *error; if (![context save:&error]) { // Handle the error... } [self.tableView reloadData]; } ``` This does not work though! Every time I want to add a row the simulator crashes and I get the following: ``` "NSInternalInconsistencyException', reason: 'This NSPersistentStoreCoordinator has no persistent stores. It cannot perform a save operation.'" ``` I had this error before I knew about creating new version after changing anything on the datamodel, but why is this still coming up? Do I need to do any mapping (even though I just added entities and properties that did not exist before?). In the Apple Dev tutorial it sounds very easy but I have been struggling with this for long time, never worked after changing model version.

Original source