I am rewriting the question to help clarify and get rid of a lot of code I wrote that really doesn't help.
I am using a .xcdatamodel for my initial schema, but I need to add entities to my schema at runtime and therefore I need to add a new NSManagedObjectModel and copy over the existing entities and then add the new entities.
If I create a new NSPersistantStore first and then ask my NSMigrationManager to migrate, I get an error about how it can't move the source model to destination path because file already exists.
If I simply ask my NSMigrationManager to migrate, then it just crashes without any error codes or anything in the debugger.
NSMappingModel *mappingModel = [NSMappingModel inferredMappingModelForSourceModel:originalModel destinationModel:newModel error:&error];
NSMigrationManager *manager = [[NSMigrationManager alloc] initWithSourceModel:originalModel destinationModel:newModel];
if (![manager migrateStoreFromURL:[originalStore URL]
type:NSSQLiteStoreType
options:[self autoMigrationOptions]
withMappingModel:mappingModel
toDestinationURL:[NSPersistentStore MR_urlForStoreName:[self nextStoreName]]
destinationType:NSSQLiteStoreType
destinationOptions:[self autoMigrationOptions]
error:&error])
{
return NO;
}
The URL's are all good, the mapping model looks good when I log it to the console, the manager exists, etc. In this case I did not create the NSPersistantStore yet, but according to the NSMigrationManager class reference if a store does not exist at the destination URL then one is automatically created.
Anyone have a clue?
Related
I've been facing a very strange problem in Realm which doesn't occur every time , but it's been really annoying.
I'm saving a lot of information offline which come from a Webservice using realm. I don't get any exception while saving all these information.
Later I'm able to get all these objects by accessing them through MyObject.allObjects().
These objects contains a property which is an UUID, which I use to download the file related to this object and save it locally, after I finish downloading the file, I update my Realm Object with the path of the file, but some times when I do it:
let pred = NSPredicate(format: "UUID = %#", fileId)
print("This is the select \(pred.predicateFormat)")
let results = IssueFile.objects(with: pred) as! RLMResults<IssueFile>
The variable results is empty, but if I check Realm Database via Realm Browser, I can find the item I'm looking for.
So my question is: why some times Realm can't find the object I'm selecting? As I'm saving a lot of information, is there something I should change in the Realm Configuration?
I've already set the UUID as primary key of the table:
+ (NSString *)primaryKey {
return #"UUID";
}
Thanks,
I'm using Back4App's service to host Parse server and I can't seem to successfully remove a field from a row. The field in question is a pointer to another object, and calling removeObjectForKey followed by a save does not work. Other updates work in the same batch, and I have seen that 4 times out the 36 that I have tried, it did successfully delete the object.
[self.myProfile removeObjectForKey:#"partnership"];
[self.myProfile saveEventually:^(BOOL succeeded, NSError * _Nullable error) {
NSLog(#"success %d", succeeded); //always returns true
}];
Is this a known problem with Back4App? Or Parse itself? I tried the same code in swift and it worked.
Any ideas?
When you need to run a callback, to confirm when is deleted, is recommended the deleteInBackgroundWithBlock: or deleteInBackgroundWithTarget:selector: methods. You can delete a single field from an object with the removeObjectForKey method:
// After this, the playerName field will be empty
[classScore removeObjectForKey:#"customName"];
// Saves the field deletion to the Parse Cloud
[classScore saveInBackground];
About the saveEventually, most save functions execute immediately, and inform your app when the save is complete. If you don’t need to know when the save has finished, you can use saveEventually instead. The advantage is that if the user currently doesn’t have a network connection.
Content from Parse =D
in my app, I want to load certain image user picks, make some modification, after that, save a copy in my own file format. Since I want to keep track of user modification, I decided to export my file as a package(bundle).
So, in my document class, there's a NSImage object that holds the image file. In the fileWrapperOfType:error: method, I've setup a NSFileWrapper object, and put the object in it. Here's the code:
NSDictionary *fileWrappers = [self.documentFileWrapper fileWrappers];
if (image != nil) {
NSBitmapImageRep *imageRep = [image bitmapImageRepresentation];
NSData *imageData = [imageRep representationUsingType:NSPNGFileType properties:nil];
NSFileWrapper *imageFileWrapper = [[NSFileWrapper alloc]
initRegularFileWithContents:imageData];
[imageFileWrapper setPreferredFilename:#"image"];
[[self documentFileWrapper] addFileWrapper:imageFileWrapper];
}
return self.documentFileWrapper;
In my project plist file, I have two document types, first is the type of public.image since I need to load images in my app:
The other one is my own document type. To make the file a package, I've checked the bundle checkbox in xcode:
If I simply run this now, the code compains that finding extension from type identifier is deprecated, so, I managed to add an entry in Exported UTIs:
At this moment, everything seems working, except that the outputed folder with mdc extension, is indeed a folder instead of a package, what am I missing here? Thanks in advance!
Finally I solved the problem, the key here is to change Conforms To field to com.apple.package.
In order for a package on OS X to be a pkg, it must have a .pkg extension. I hope it is as simple as having the wrong extension.
Note: Until recently, .pkg files were merely directories. Now, we often see package.pkg packages that are obscured cannot be browsed causually without some tricks like using Pacifist, pkgutil or xar:
pkgutil --extract file.pkg folder/
or
xar -xf file.pkg
I have two versions of my model Model001.xcdatamodel and Model002.xcdatamodel. These two are in the Model.xcdatamodeld bundle.
I also have a Model001to002.xcmappingmodel which is not part of the Model.xcdatamodeld. I checked: both the xcmappingmodel and the xcdatamodeld get copied into the .app bundle.
My managed object context is initialized like this:
NSURL *documentModel = [bundle URLForResource:#"Model"
withExtension:#"momd"]; managedObjectModel = [[NSManagedObjectModel alloc]
initWithContentsOfURL:documentModel]; return managedObjectModel;
I also set these properties on my overridden initWithFileURL: in my UIManagedObject subclass.
NSMutableDictionary *options = [NSMutableDictionary dictionaryWithDictionary:self.persistentStoreOptions];
[options setObject:#YES forKey:NSMigratePersistentStoresAutomaticallyOption];
[options setObject:#YES forKey:NSInferMappingModelAutomaticallyOption];
self.persistentStoreOptions = [options copy];
But when I try to open a documet, I get the following error:
Can't find mapping model for migration
-- UPDATE --
Even if I do a manual migration
[NSMappingModel mappingModelFromBundles:#[[NSBundle mainBundle]]
forSourceModel:sourceObjectModel
destinationModel:self.managedObjectModel];
this returns nil. Although I double checked that the Model001to002.cdm is in the app bundle. It has to be in the app bundle right?
A "gotcha" with mapping models is that you are not allowed to make any changes to the models after you created the mapping. If you do, you will also get this error.
OK, solved the problem by removing all core data files from Xcode, reading them and setting the source and destination of the mapping model again.
Damn you Xcode!
You are not allowed to make any changes to the source/destination model after you have created the mapping models.
If you do make some changes,
mappingModelFromBundles:forSourceModel:destinationModel: will not be able to find the mapping model file
addPersistentStoreWithType:configuration:URL:options:error: with {NSInferMappingModelAutomaticallyOption: #NO} will report an error "Can't find mapping model for migration"
migrateStoreFromURL:type:options:withMappingModel:toDestinationURL:destinationType:destinationOptions:error: will report an error "Mismatch between mapping and source/destination models"
So, just recreate the mapping model and copy every change you made in the old one.
TL;DR
At least as of Xcode 8/9, open the mapping model then from the Editor menu select Refresh data models. Usually it seems you need to restart Xcode. If that doesn't do it you might try re-selecting the destination at the bottom of the model editor.
More Tips
Definitely NEVER change a model after it has been distributed in an app build.
For this example, let's say you have published Data Model 1 (DM1) and are making a migration to DM2. If you set DM2 as the active version then run your app, a migration will run on your persistent store. If you then make another change to DM2, run your app... Boom!
The issue is that your store has already been migrated to "DM2" but the data in the store doesn't fit into the model anymore. And, we can't migrate from DM2 to DM2 again.
It may seem like an obvious solution to go ahead and create DM3. It is
usually a good idea though to minimize the number of models and
migrations while you are developing.
So... now you have a persistent store that has been migrated to a defunct DM2. How do you test the migration again? You could revert your app and generate some data with DM1 but I prefer to use backups
Creating a backup
Before you run your app with DM2 you can copy the existing store (with DM1) to use for later test migrations. On macOS you can easily do this manually. The code below should do the trick as well. Typically you wouldn't want to ship this, rather you could just put it somewhere before your normal CD stack opens, run the app, then stop the app (maybe place a breakpoint just after then end the run via Xcode).
let fm = FileManager.default
let url = // The store URL you would use in ↓
// try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
let dir = url.deleteLastPathComponent().appendingPathComponent("Backup", isDirectory: true).appendingPathComponent("DM1", isDirectory: true)
print("Saving DB backup for DM1")
if !fm.fileExists(atPath: dir.path) {
do {
// Create a directory
try fm.createDirectory(at: dir, withIntermediateDirectories: true, attributes: nil)
let backupURL = dir.appendingPathComponent(url.lastPathComponent)
try fm.copyItem(at: url, to: backupURL)
}
catch {
print("Failed to save DB backup")
}
}
Oops, I need to make another change...
If you run your migration to DM2 then realize you need to make another change, you'll want to re-test your migration from DM1 -> DM2. This is where the backup comes in.
Same way you made the backup, run this code.
let fm = FileManager.default
let url = // The store URL you would use to add the store
let dir = url.deleteLastPathComponent().appendingPathComponent("Backup", isDirectory: true).appendingPathComponent("DM1", isDirectory: true)
let backupURL = dir.appendingPathComponent(url.lastPathComponent)
if fm.fileExists(atPath: backupURL.path) {
do {
fm.removeItem(at: url.path)
try fm.copyItem(at: backupURL, to: url)
}
catch {
print("Failed to restore DB backup")
}
}
You now have a restored DM1 store and have made changes to DM2. If you run the app the migration might succeed but it won't use your custom mapping model.
Remember if you are using a custom mapping, you will still need to use the Refresh Data Models technique before the mapping model will work.
This can happen if your test device's store is from a version of the data model that no longer exists.
For example I had Data Model Version 7, then I made Data Model Version 8. I made a mapping model to go from 7 to 8. Then I ran it on my test device and everything was happy.
Then I made some more changes to 8.
The thing to realize is that in Core Data, every model has a hash identifier that the system creates by taking a checksum of the xcdatamodel file. So if you make even a slight change, even if you didn't create a new version, it sees it as a different version. These versions' identifiers are NSStoreModelVersionHashes (see documentation here).
So in other words, I ended up with:
Data Model 7 (release) - 0plcXXRN7XHKl5CcF+fwriFmUpON3ZtcI/AfK748aWc=
Data Model 8 (beta) - qeN1Ym3TkWN1G6dU9RfX6Kd2ccEvcDVWHpd3LpLgboI=
Data Model 8 (release) - EqtMzvRnVZWkXwBHu4VeVGy8UyoOe+bi67KC79kphlQ=
Instead of making a version 9, and saving the original version 8 in the data model history, I just updated 8, figuring automatic migration could take care of me. Well, it couldn't, and I couldn't make a mapping between the two, because the old (beta) version of 8 was gone.
I did it that way because it was an intermediary internal build (not a release) so it wasn't a big deal, but it did throw me for a loop!
If it wasn't an internal build and I needed to make this work, I could go back to the (beta) commit and pull out that xcdatamodel file for 8 (beta), rename the (release) version to 9, then stick it into the release build and make a mapping model between 8 and 9.
However since it was just an internal beta build, we just erased and reinstalled the app on test devices. We did verify that, when going from 7 (release) to 8 (release), the migration went smoothly.
Removing Coredata files from its path an re - run project is worked for me
My setup
The following all works fine:
RKManagedObjectMapping* chanMapping = [RKManagedObjectMapping mappingForClass:[Channel class] inManagedObjectStore:objectStore];
chanMapping.primaryKeyAttribute = #"chanId";
[chanMapping mapKeyPathsToAttributes:
#"id",#"chanId",
#"name", #"chanName",
nil];
[objectManager.mappingProvider setMapping:chanMapping forKeyPath:#"Channels.channel"];
I can call
[[RKObjectManager sharedManager] loadObjectsAtResourcePath:#"/channels" delegate:self];
and I get my channel's from the server and they're stored locally by Core Data. Perfect.
The issue
However, I now wan't to have RestKit automatically delete Channels from the Core Data store that have been removed from the server the next time a GET is performed. I understand this is supported by adding the following:
[objectManager.mappingProvider setObjectMapping:chanMapping forResourcePathPattern:#"/channels" withFetchRequestBlock:^ (NSString *resourcePath) {
return [Channel fetchRequest];
}];
However with this all the Channels get deleted whenever there is anything new on the server.
Things I've tried [UPDATED]
I've debugged using the steps in the answer below. It looks as though the mapping isn't working / is not being found (i.e. I haven't properly associated the mapping with the resource path).
In deleteCachedObjectsMissingFromResult the cachedObjects array looks good, has all the objects that should be there from the last time but the results array is empty which obviously results in [results containsObject:object] always being NO and all the objects being deleted.
Do I need to change something to do with the resource path mapping?
I looked at your updated description. Give this a try:
Switch back to the setObjectMapping:forResourcePathPattern:withFetchRequestBlock
Set the rootKeyPath on the object mapping you register to Channels.channel
Then give it another try. There is some API work in progress to provide URL and keyPath based mapping configuration in a single line, but its not merged to development yet.
Two things to check out to determine why you are seeing the described behavior:
Open up RKManagedObjectLoader and put a breakpoint within isResponseMappable. This method checks if the response was loaded from the cache and performs a load of the objects using the objects returned by the managed object cache if it returns YES. This is probably where you are seeing the return of the cached objects from.
As for the deletion of cached objects, put a breakpoint within deleteCachedObjectsMissingFromResult and see what is going on in there (if you are even making it into the routine).
The scenario to expect automatic pruning would be:
GET /channels returns 2xx status code with new payload
RKManagedObjectLoader performs pruning