I am loading a NSManagedObjectModel model with the initWithContentsOfURL: constructor like this:
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"MyDocument" withExtension:#"momd"];
NSManagedObjectModel *mom = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
However this only gives me access to the latest/current version of a model. Is it posible to load previous versions with the same momd file? how?
Actually you can load an older version with:
- (NSManagedObjectModel *)managedObjectModelForVersion:(NSString *)version
{
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:[NSString stringWithFormat:#"AppModel.momd/AppModel %#",version] withExtension:#"mom"];
NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return model;
}
Just replace AppModel with your model name.
I'm using this to get myself out of a sticky manual migration situation involving iCloud. Searched high and low and couldn't find this anywhere.
If you just want to load the version of the model that's compatible with a particular existing store try:
NSError *error = nil;
NSDictionary *storeMetadata = [NSPersistentStoreCoordinator metadataForPersistentStoreOfType:NSSQLiteStoreType
URL:storeURL
error:&error];
NSManagedObjectModel *oldManagedObjectModel = [NSManagedObjectModel mergedModelFromBundles:[NSArray arrayWithObject:[NSBundle mainBundle]]
forStoreMetadata:storeMetadata];
Note that if you use XCode version identifiers for your data model versions, the persistent store's current version identifiers are accessible through the NSStoreModelVersionIdentifiersKey entry in the store metadata dictionary.
As far as loading a particular arbitrary version is concerned, the mom files are typically located under the momd directory in your app's bundle, so you could enumerate them using NSFileManager. I believe to find one with a particular version identifier you would have to use NSManagedObjectModel's initWithContentsOfURL: initializer and then inspect the versionIdentifiers property, or use the isConfiguration:compatibleWithStoreMetadata: instance method to determine compatibility.
Made the solution offered by #Schoob into a category, because they rock.
#interface NSManagedObjectModel (version)
+ (NSManagedObjectModel *)modelFromBundle:(NSBundle *)bundle name:(NSString *)modelName version:(NSString *)version;
#end
#implementation NSManagedObjectModel (version)
+ (NSManagedObjectModel *)modelFromBundle:(NSBundle *)bundle name:(NSString *)modelName version:(NSString *)version
{
if(!bundle)
bundle = [NSBundle mainBundle];
NSString *resource = [[modelName stringByAppendingPathExtension:#"momd"] stringByAppendingPathComponent:version];
NSURL *modelURL = [bundle URLForResource:resource withExtension:#"mom"];
NSAssert(modelURL,#"Unable to find MOM - %#",resource);
NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
NSAssert(model,#"Unable to load MOM at URL- %#",modelURL);
return model;
}
#end
Swift version. Replace file name.
import CoreData
extension NSManagedObjectModel
{
class func model(forVersion version: Int) -> NSManagedObjectModel?
{
if let fileUrl = Bundle.main.url(forResource: "Model.momd/Model \(version)", withExtension: "mom")
{
return NSManagedObjectModel(contentsOf: fileUrl)
}
return .none
}
}
No, it is not foreseen that this is possible. I deduce that from the NSManagedObjectModel documentation, where it says discussing the property versionIdentifiers:
This value is meant to be used as a debugging hint to help you determine the models that were combined to create a merged model.
So it does not seem you are supposed to use previous model versions for your program logic.
Related
I have added new attribute and I need to migrate core data. As a result, I do like this.
Bus.xcDataModel >> Add model version
Then, I add new attribute. I change persistent store coordinator option as well like this.
#{NSMigratePersistentStoresAutomaticallyOption:#YES, NSInferMappingModelAutomaticallyOption:#YES}
But when I add that new attribute, it show me like this. How shall I do?
-[BusService setBus_wap:]: unrecognized selector sent to instance 0x1742a7320
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator_busservice
{
if (_persistentStoreCoordinator_busservice != nil)
return _persistentStoreCoordinator_busservice;
NSURL *applicationDocumentsDirectory = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
NSURL *storeURL = [applicationDocumentsDirectory URLByAppendingPathComponent:#"Busservice_new.sqlite"];
if (![[NSFileManager defaultManager] fileExistsAtPath:[storeURL path]] &&
!self.preloadEnabled)
{
NSURL *preloadURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:#"Busservice_new" ofType:#"sqlite"]];
NSError* err = nil;
if (![[NSFileManager defaultManager] copyItemAtURL:preloadURL toURL:storeURL error:&err])
DLog(#"Oops, could not copy preloaded data");
}
NSError *error = nil;
_persistentStoreCoordinator_busservice = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator_busservice addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:#{NSMigratePersistentStoresAutomaticallyOption:#YES, NSInferMappingModelAutomaticallyOption:#YES} error:&error])
{
DLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator_busservice;
}
From that error it looks like you added a new attribute to your BusService entity in Core Data, but did not add the attribute to your BusService class. If you want to use accessor methods for this new attribute, you need to update the class as well. Or you can leave the class alone but use setValue:forKey: to assign values to the new attribute.
In upgrading my application from v1 to v2, I've made a few small changes to the Core Data Model. The changes are just adding new attributes to the models.
I have versioned the data model with the before and after changes and implemented the following code in my App Delegate:
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (__persistentStoreCoordinator != nil)
{
return __persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"ISDEmployees.sqlite"];
NSLog(#"storeURL:%#",storeURL);
NSError *error = nil;
// Create a dictionary for automatic lightweight core data migration
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
nil];
__persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
// Set up the persistent store and migrate if needed
if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error])
{
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return __persistentStoreCoordinator;
}
Basically the standard persistentStoreCoordinator with the addition of the migration options. This code works great and my database is successfully updated. The problem that I'm having is that after the database update, I need to refresh all of the data in the database so that the new columns are populated. I was thinking that I would delete the data from the relevant entities/tables and force the application to re-download a new dataset with the added columns/attributes.
I'm not sure how/where to perform the delete/updates. The general application flow is this:
Log in with validation against an web API
On successful login, call the API and get latest added/updated records.
Display the updated data
I know I can check to see if a migration is needed by adding this code to persistentStoreCoordinator:
// Get the current data store meta data
BOOL migrationNeeded = NO;
NSDictionary *existingStoreData = [NSPersistentStoreCoordinator metadataForPersistentStoreOfType:NSSQLiteStoreType URL:storeURL error:&error];
if (existingStoreData)
{
// Check to see if new model is not the same as the existing mode, meaning a migration is required
if (![self.managedObjectModel isConfiguration:nil compatibleWithStoreMetadata:existingStoreData])
{
migrationNeeded = YES;
}
}
Any help would be greatly appreciated!!
Update #1:
Based on the feedback below, I've made the following changes:
Changed the migrationNeeded from a local to a public class variable on the AppDelegate.
On the Login View, I've added the following method:
- (void)checkForDatabaseMigration
{
// Get a copy of the managed object context. If a migration is needed, it will kick it off
NSManagedObjectContext *managedObjectContext = [(AppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
if ([(AppDelegate *)[[UIApplication sharedApplication] delegate] migrationNeeded])
{
// Delete all data from the table
}
managedObjectContext = nil;
}
Does that seem right? The code works and the data is removed after migration and a fresh copy is inserted. I just hate to check for migration each time the application starts.
If you know how to determine when to delete old data, all you need is to fetch all the enteties you need and delete them. Here is how you do that(for example, if you want to delete all Man enteties):
NSFetchRequest * request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:#"Man" inManagedObjectContext:myContext]];
[request setIncludesPropertyValues:NO]; //only fetch the managedObjectID
NSError * error = nil;
NSArray * men = [myContext executeFetchRequest:request error:&error];
//error handling goes here
for (NSManagedObject * man in men) {
[myContext deleteObject:man];
}
NSError *saveError = nil;
[myContext save:&saveError];
//more error handling here
I can load my model with mergedModelFromBundles: just fine. But when I try to initialize them manually with initWithContentsOfURL:, they are nil.
I share them in 2 projects. This load code is in one file shared in the projects as well. Everything works as expect in the first project but the second project is giving me issues.
NSMutableArray *models = [NSMutableArray array];
NSString *path = [[NSBundle mainBundle] pathForResource:#"MyModel" ofType:#"momd"];
if(![[NSFileManager defaultManager] fileExistsAtPath:path]){
NSLog(#"Compiled MyModel.momd file not found.");//never gets called, file is there
}
NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL: [NSURL URLWithString:path] ];
if(!model){
//this is getting called which indicates there is something wrong with the coredata file...?
NSLog(#"Could not load compiled MyModel.momd file.");
}else{
[models addObject:toolKitModel];
}
//works in project 1 where initWithContentsOfURL: returns nil but not in project 2
_managedObjectModel = [NSManagedObjectModel mergedModelFromBundles: NULL ];
//works in project 2 where initWithContentsOfURL: returns the NSManagedObjectModel but not in project 1
_managedObjectModel = [NSManagedObjectModel modelByMergingModels:models ];the models
Any ideas why the NSManagedObjectModel won't load with initWithContentsOfURL: and modelByMergingModels:?
The code bellow add to Core data issues, but after it added, I can't save with error (multiply validation error occured)
MySQLIXC *ixcDatabase = [[MySQLIXC alloc] init];
NSArray *destinationsForSaleList = [ixcDatabase destinationsForSaleList:carrier];
NSFetchRequest *request1 = [[[NSFetchRequest alloc] init] autorelease];
[request1 setEntity:[NSEntityDescription entityForName:#"DestinationsList"
inManagedObjectContext:managedObjectContext]];
for (NSDictionary *destinationsForSale in destinationsForSaleList) {
NSManagedObject *object1 = [NSEntityDescription
insertNewObjectForEntityForName:#"DestinationsList"
inManagedObjectContext:managedObjectContext];
NSLog(#"Moc: %#",managedObjectContext);
[object1 setValue:#"y" forKey:#"weAreSoldIt"];
// changeDate
NSString *chdate = [destinationsForSale objectForKey:#"chdate"];
NSDateFormatter *changeDate = [[[NSDateFormatter alloc] init] autorelease];
[object1 setValue:[changeDate dateFromString:chdate] forKey:#"changeDate"];
NSLog(#"Carrier :%# Destination name:%#",carrier, destinationsForSale);
//Country
[object1 setValue:[destinationsForSale objectForKey:#"country"] forKey:#"country"];
//rate
NSNumberFormatter *rate = [[[NSNumberFormatter alloc]init ]autorelease];
[object1 setValue:[rate numberFromString:[destinationsForSale objectForKey:#"price"]] forKey:#"rate"];
Unfortunately I can't fix a bug by the way which u propose bellow.
Bcs Entity DestinationList must have relations with Entity Carriers by project understanding.
That is how I try to fix it:
[objectDestinationList setValue:objectCarrier forKey:#"carrier"];
I was send to method my carrier object as object, but it doesn't work.
In this case, I don't know how is a way to fix it around. Bcs I see error, but don't see case why error is start.
Do u know a simple code to correct add relationships to Entity? All what I catch around internet is a core data book ,my Marcus Zarra and his very hard to understanding example. His showing a complex solution, I can understand it, but using programming style which not very easy for me at this moment (according my one month experience in cocoa programming ;)
Here is additional information: How I create Carrier instance. I have managedObjectContext, which I receive to class from AppDelegate.
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:[NSEntityDescription entityForName:#"Carrier"
inManagedObjectContext:managedObjectContext]];
NSManagedObject *carrier = [managedObjectContext executeFetchRequest:request error:&error]
by the same way I prepare NSManagedObject for DestinationsList Entity.
After that I add all values to NSManagedObject for destinationsList, I have to make relationship between Carrer NSManagedObject and destinationsList. In this case I have trouble. Bellow is how I try to update relationship for Carrier entity:
NSSet *newDestSet = [NSSet setWithObjects:objectDestination,nil];
[objectCarrier setValue:newDestSet forKey:#"destinationsList"];
finally I have 2010-11-03 21:22:56.968 snow[20301:a0f] -[NSCFArray initialize]: unrecognized selector sent to instance 0x1c44e40
Bellow is my class interface deescription:
#interface InitUpdateIXC : NSObject {
NSInteger destinationType;
}
-(void) updateCarrierList:(NSManagedObjectContext *)managedObjectContext;
-(void)updateDestinationList:(NSManagedObjectContext *)managedObjectContext
forCarrier:(NSString *)carrierName
forCarrierObject:(NSManagedObject *)objectCarrier
destinationType:(NSInteger)destinationType;
#end
Yep, bellow in answer present correct model, but some different is here.
At first, i don't have separate class for Entity as u present in you model. My current class is just NSManagedObject
In second, relationship "carrier" is non-optional for Entity DestinationsList.
SOLUTION AND ERROR DESCRIPTION:
In case of trouble, what happened with my code:
When i try to add setValue forKey with back relationship from DestinationsList to Carrier, i forget that NSManagmentObject return every time array, not just object.
This is a reason why i receive error about array init problem.
Solution is not sent Carrier object to method, bcs for me was too hard to extract from array correct object without key value. I was using a predicate access to extract object to array and lastObject function to extract correct object from array. After that i set accroding value and everything working fine.
A solution not look like cocoa-style, so better way is refactor it in future, any suggestion wellcome.
Here is appropriate code:
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:[NSEntityDescription entityForName:#"Carrier"
inManagedObjectContext:managedObjectContext]];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"name =%#",carrierName];
[request setPredicate:predicate];
NSError *error = nil;
NSArray *currentCarriers = [managedObjectContext executeFetchRequest:request error:&error];
[objectDestination setValue:[currentCarriers lastObject] forKey:#"carrier"];
Try adding something like this for you 'save'
NSError *error = nil;
if (![managedObjectContext save:&error])
{
// Handle the error.
NSLog(#"Failed to save to data store: %#", [error localizedDescription]);
NSArray* detailedErrors = [[error userInfo] objectForKey:NSDetailedErrorsKey];
if(detailedErrors != nil && [detailedErrors count] > 0)
{
for(NSError* detailedError in detailedErrors)
{
NSLog(#" DetailedError: %#", [detailedError userInfo]);
}
}
else
{
NSLog(#" %#", [error userInfo]);
}
}
At least, then you can see what the multiple errors are. If you post those, someone may be able to offer more help.
One thought, though, is that there is something buggy about your data model - like non-optional attribute with no value, etc.
If you create NSManagedObject subclassed Carrier and DestinationsList, then in Carrier.h you should have some method declarations like this. (Assuming that Carrier to-many DestinationsList is called 'destinationsLists'.)
#interface Carrier (CoreDataGeneratedAccessors)
- (void)addDestinationsListsObject:(Run *)destinationsList;
- (void)removeDestinationsListsObject:(Run *)destinationsList;
- (void)addDestinationsLists:(NSSet *)destinationsLists;
- (void)removeDestinationsLists:(NSSet *)destinationsLists;
#end
Once these are declared, you should be able to add a DestinationsList to a Carrier with a line like this:
[myCarrier addDestinationsListsObject:myDestinationsList];
Not seeing your full data model, it is difficult to know what is happening and what would help fix it.
Do you have something like this for your model definition?
Can someone please shed some light on how I would get this to work:
http://www.icab.de/blog/2009/08/18/url-filtering-with-uiwebview-on-the-iphone/
I tried making the "FilteredWebCache.h" and "FilteredWebCache.m" files in my project, but it said that "FilterManager.h" did not exist. What am I meant to do with those files?
This I put in viewDidLoad:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex:0];
NSString *path = docDir; // the path to the cache file
NSUInteger discCapacity = 10*1024*1024;
NSUInteger memoryCapacity = 512*1024;
FilteredWebCache *cache = [[FilteredWebCache alloc] initWithMemoryCapacity:memoryCapacity diskCapacity:discCapacity diskPath:path];
[NSURLCache setSharedURLCache:cache];
[cache release];
You need to write the FilterManager class yourself (FilterManager.m and FilterManager.h). That post says:
The code first checks if the URL should be blocked (the FilterManager class is doing all these checks, this class isn’t shown here).
The example code seems to call it FilterMgr instead of FilterManager, and it looks like you need to provide a shouldBlockURL: method that decides what gets blocked.
BOOL blockURL = [[FilterMgr sharedFilterMgr] shouldBlockURL:url];