我正在尝试扩展我的核心数据。所以我向我的实体添加了一个新属性,并尝试使用Automatic Lightweight Migration。但是当我启动程序时,会弹出错误Persistent store migration failed missing source managed object model
。
任何人都知道出了什么问题?
我的AppDelegate.c的相关部分(事实上我只添加了NSDictionary *options
):
- (NSPersistentStoreCoordinator *) persistentStoreCoordinator {
if (persistentStoreCoordinator) return persistentStoreCoordinator;
NSManagedObjectModel *mom = [self managedObjectModel];
if (!mom) {
NSAssert(NO, @"Managed object model is nil");
NSLog(@"%@:%@ No model to generate a store from", [self class], _cmd);
return nil;
}
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *applicationSupportDirectory = [self applicationSupportDirectory];
NSError *error = nil;
if ( ![fileManager fileExistsAtPath:applicationSupportDirectory isDirectory:NULL] ) {
if (![fileManager createDirectoryAtPath:applicationSupportDirectory withIntermediateDirectories:NO attributes:nil error:&error]) {
NSAssert(NO, ([NSString stringWithFormat:@"Failed to create App Support directory %@ : %@", applicationSupportDirectory,error]));
NSLog(@"Error creating application support directory at %@ : %@",applicationSupportDirectory,error);
return nil;
}
}
NSURL *url = [NSURL fileURLWithPath: [applicationSupportDirectory stringByAppendingPathComponent: @"stats.darx"]];
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: mom];
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:url
options:options
error:&error]){
[[NSApplication sharedApplication] presentError:error];
[persistentStoreCoordinator release], persistentStoreCoordinator = nil;
return nil;
}
return persistentStoreCoordinator;
}
答案 0 :(得分:3)
您需要使用版本化的托管对象模型,其中包含两个版本的模型。自动迁移仍然需要查看模型的现有版本和新版本,以便找出差异是什么以及如何处理它们。
您引用的错误表明您的应用包现在只包含您的新模型(您要使用的模型),而不是旧模型(您尝试从中迁移的模型)。返回到您的版本控制系统并检索旧模型,然后设置一个版本化模型,其中包含旧模型为v1,新模型为v2。