I am working on IOS. I am using realm database in the frontend. It was working fine until I made some changes to the realm model and all files related to it. I just added one field to these files.
Now I am getting an error "Fatal error: Can't open realm" in the following code
fileprivate func getRealm() -> Realm {
// get default configuration realm
do {
return try Realm()
} catch {
Swift.fatalError("Can't open realm") //Fatal Error :Can't open realm
}
}
Can anyone tell what might be the possible causes for this error.
Thanks in advance.
If you made changes to the realm model, you need to increase your schema version and you may or may need to provide a migration block. See the official documentation for details.
// Inside your [AppDelegate didFinishLaunchingWithOptions:]
RLMRealmConfiguration *config = [RLMRealmConfiguration defaultConfiguration];
// Set the new schema version. This must be greater than the previously used
// version (if you've never set a schema version before, the version is 0).
config.schemaVersion = 1;
// Set the block which will be called automatically when opening a Realm with a
// schema version lower than the one set above
config.migrationBlock = ^(RLMMigration *migration, uint64_t oldSchemaVersion) {
// We haven’t migrated anything yet, so oldSchemaVersion == 0
if (oldSchemaVersion < 1) {
// Nothing to do!
// Realm will automatically detect new properties and removed properties
// And will update the schema on disk automatically
}
};
// Tell Realm to use this new configuration object for the default Realm
[RLMRealmConfiguration setDefaultConfiguration:config];
// Now that we've told Realm how to handle the schema change, opening the file
// will automatically perform the migration
[RLMRealm defaultRealm];
The above issue is caused due to inconsistency in the Realm database. I changed the structure of the model by adding one field. So, the model was having 10 fields but the realm database in my app was having 9 fields, as the app was built before the changes.
I solved the issue by just reinstalling the app which regenerated the realm database in the phone, thereby having a consistent model and database.
The above workaround might be good if your app is yet to be live. But, if your app is already being used by other users, then they will have to reinstall the app on update, which might result in bad user experience for the user.
Ideally, you should be writing a migration block for the new changes.
Hope, this is clear to all.
Related
suppose latest app release version is version no 20. and there are 10 coredata migrations so far till version no 20.
and for example: a user which is using version 3. directly do auto update to version no 20.
i want to delete coredata stack and rebuild it then.
but does it solve that model update issue ? means version 3 uses v3 data model update (xcdatamodel) and version 20 uses v20 data model update(xcdatamodel).
if i delete and rebuild coredata with below code when user autoupdate app from version 3 to 20.
then will it also point to new xcdatamodel version ?
var allstores : Array = self.storeContainer.persistentStoreCoordinator.persistentStores
for store in allstores{
// remove store file from coordinator
do {
try storeContainer.persistentStoreCoordinator.destroyPersistentStore(at: store.url!, ofType: NSSQLiteStoreType, options: nil)
} catch let error {
print("\(error.localizedDescription)")
}
}
and then rebuild..
self.storeContainer.loadPersistentStores(completionHandler: { (nsPersistentStoreDescription, error) in
guard let error = error else {
return
}
fatalError(error.localizedDescription)
})
Yes. I implemented this strategy once I decided to rebuild the database when it was incompatible with older versions. Side node: now I just rely on CoreData to handle the migration.
To test if it works, create an entity with a non-mandatory field and insert a row for that entity without a value for that field. Now in your new data model, make that exact same field mandatory. Now what you will see is an app crash if you don't destroy the persistent store and rebuild it, as you are showing in your code. However, if you rebuild it, it will work.
Note that the user has lost all of his data, but I presume you already know that. I had some code that queried the database for existing data and it copied the local cache from the server.
After updating XCode to version 11 I added a new model version to Core Data and in new version I added a new attribute to an Entity. Made the new version active and added the new property to managed object file.
After releasing this version to the users it started to crash with the following message: "The managed object model version used to open the persistent store is incompatible with the one that was used to create the persistent store." and "duplicate column name ZNEWCOLUMN". Until now I made a lot of changes to the Core Data model and migration always worked.
This crash appears only on iOS 13!
This is how I load Core Data:
lazy var managedObjectContext: NSManagedObjectContext = {
return self.persistentContainer.viewContext
}()
lazy var persistentContainer: NSPersistentContainer = {
/*
The persistent container for the application. This implementation
creates and returns a container, having loaded the store for the
application to it. This property is optional since there are legitimate
error conditions that could cause the creation of the store to fail.
*/
let container = NSPersistentContainer(name: "MyModel")
container.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error as NSError? {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
/*
Typical reasons for an error here include:
* The parent directory does not exist, cannot be created, or disallows writing.
* The persistent store is not accessible, due to permissions or data protection when the device is locked.
* The device is out of space.
* The store could not be migrated to the current model version.
Check the error message to determine what the actual problem was.
*/
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
let description = NSPersistentStoreDescription()
description.shouldInferMappingModelAutomatically = true
description.shouldMigrateStoreAutomatically = true
container.persistentStoreDescriptions.append(description)
return container
}()
Any help would be appreciated.
The same thing is happening to me, lightweight migration at iOS 12 was right at real device and Simulator but at iOS 13 fail with the next log result:
SQLite error code:1, 'duplicate column name: ZNAME_OF_THE_COLUMN .... Error Domain
= NSCocoaErrorDomain Code = 134110 "An error occurred during persistent storage migration."
I load data like #iOS Dev post.
I check the xxxx.sqlite database file in the emulator path before and after the migration and there were no columns with those new same names.
To know the route of the *.sqlite in emulator you have to put a breakpoint and when it is stopped put in the console po NSHomeDirectory().
Then go to Finder window, tap the keys Control + Command + G and paste the route. Yo can handle it (for example) with DB Browser for SQLite program, it´s free.
After a long search I have seen what has happened to some people but I have not seen any solution.
Mine was:
Select the actual *.xcdatamodel.
Select Editor > Add Model Version.
Provide a version name based on the previous model (like XxxxxxV2.xcdatamodel).
Click on this new version model NewV2.xcdatamodel.
Select this new version as Current on Properties at right hand of IDE.
Make your changes at DDBB.
Run app and will work fine.
I did tests overriding app (with new values) and it was fine.
I hope this may help.
If you want to edit the descriptions, you need to do so before you load the stores (and I have no idea what appending a new description would do):
container.persistentStoreDescriptions.forEach { storeDesc in
storeDesc.shouldMigrateStoreAutomatically = true
storeDesc.shouldInferMappingModelAutomatically = true
}
container.loadPersistentStores { [unowned self] (storeDesc, error) in
if let error = error {
// handle your error, do not fatalError! even a message that something is wrong can be helpful
return
}
// do any additional work on your view context, etc.
}
If your problem is reproduceable, you should look at the error that's being returned and look for something called ZNEWCOLUMN (though this sounds like a temporary default name?) This nomenclature is the raw column name in the SQL database though, so it's likely the migrator is attempting to add this new column and failing.
Try turning on SQL debugging in your scheme's Arguments:
-com.apple.CoreData.SQLDebug 1
Try logging into the raw SQL database (the above will give you the raw path if you're on the simulator). Try rolling back to the previous data model on a previous OS and then just upgrading to 13.
Sounds like you have some duplicate column somewhere so these are just some ideas to find out where it is.
Performing migrations on a Realm database is poorly documented and the documentation seems to be out-of-date. There are two areas explaining how to migrate data:
-- The simple example on the Realm website: https://realm.io/docs/swift/latest/
-- A more detailed example in the Github examples section: https://github.com/realm/realm-cocoa/blob/master/examples/ios/swift-3.0/Migration/AppDelegate.swift
Neither of these examples adequately explain how to migrate data between schema versions. I've tried playing around with the examples and have yet to get any migrations working. As well, I've had problems with app crashes when upgrading to newer Realm versions without schema changes and data changes, which don't occur in the Simulator but occur when installing the app from TestFlight or the App Store.
Seems like the Realm documentation and examples detailing migrations are due for a refresh. My areas of interest are:
Upgrading to a newer Realm version without a schema change in the database. Unclear whether I should continue using the default.realm file generated with a previous version, or whether I need to re-generate the default.realm file using the newer Realm framework version.
Adding a new attribute to a Realm object.
New objects ("rows") added to an existing class without any schema change.
No schema changes to existing classes in the database, but addition of an entirely new class or classes.
Any combination of the above.
Thanks!
Sorry the docs are not sufficient. We appreciate the feedback and will use it to improve them. In the mean time, let me answer your questions:
You do not need to do anything when you upgrade the SDK. Sometimes, we upgrade the core database file format, but this migration happens automatically when you open the Realm (Realm()) so you don't have to worry about it.
When you add a new property to an object you can just follow this code snippet.
Nothing is needed in the migration block since this block is simply to apply data transformations between versions. All you need to do is increment the schemaVersion
// Inside your application(application:didFinishLaunchingWithOptions:)
let config = Realm.Configuration(
// Set the new schema version. This must be greater than the previously used
// version (if you've never set a schema version before, the version is 0).
schemaVersion: 1,
// Set the block which will be called automatically when opening a Realm with
// a schema version lower than the one set above
migrationBlock: { migration, oldSchemaVersion in
// We haven’t migrated anything yet, so oldSchemaVersion == 0
if (oldSchemaVersion < 1) {
// Nothing to do!
// Realm will automatically detect new properties and removed properties
// And will update the schema on disk automatically
}
})
// Tell Realm to use this new configuration object for the default Realm
Realm.Configuration.defaultConfiguration = config
// Now that we've told Realm how to handle the schema change, opening the file
// will automatically perform the migration
let realm = try! Realm()
Adding objects to a Realm does not affect the schema so a migration is not relevant.
This is the same as 2, you simply need to increment the schemaVersion but you don't have to do anything in the migration block since Realm handles everything. The migration block is for custom migration logic where, for example, you want to transform firstName and lastName from schemaVersion=0 to fullName when updating to schemaVersion=1. In this case, you could get the data from the old version and concatenate the strings into the new fullName property within the migration block.
Hope this helps!
Unfortunately, that doesn't work, at all. There is a block of code I had to add to iOS apps several months ago in order to get Realm to work, but it doesn't solve the migration problems I've experienced:
config.fileURL = config.fileURL!.deletingLastPathComponent().appendingPathComponent("default-v1.realm")
Realm.Configuration.defaultConfiguration = config
// copy over old data files for migration
//let defaultURL = Realm.Configuration.defaultConfiguration.fileURL!
let defaultURL = Realm.Configuration.defaultConfiguration.fileURL!
//print("Realm.Configuration.defaultConfiguration.fileURL! = \(defaultURL)")
//let defaultParentURL = defaultURL.URLByDeletingLastPathComponent
if let realmURL = bundleURL("default-v1") {
do {
//print("Bundle location for default.realm = \(realmURL)")
let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
let url = URL(fileURLWithPath: path)
let filePath = url.appendingPathComponent("default-v1.realm").path
let fileManager = FileManager.default
if fileManager.fileExists(atPath: filePath) {
print("FILE INSTALLED")
print("Documents location for default.realm = \(filePath)")
} else {
//print("FILE NOT INSTALLED, COPYING default.realm from bundle to Documents directory.")
try FileManager.default.copyItem(at: realmURL, to: defaultURL)
}
} catch {}
}
I suspect that a new default-v1.realm file may clobber an existing default-v1.realm file on a user's device, using this code with the "Nothing is needed" migration method.
Part of the confusion stems from the example migration code at https://github.com/realm/realm-cocoa/tree/master/examples/ios/swift-3.0/Migration where data from the v1 file is getting copied over to the v2 file. Regardless, I've tried the "Nothing is needed" code you've posted and the app doesn't find any Realm data then crashes.
It looks like I could splice the code you've posted into the code I've been using then perhaps that would solve the problem. Will look into that next week.
Thanks for your response!
In the realm docs I see the code example for migrations
let config = Realm.Configuration(
// Set the new schema version. This must be greater than the previously used
// version (if you've never set a schema version before, the version is 0).
schemaVersion: 1,
// Set the block which will be called automatically when opening a Realm with
// a schema version lower than the one set above
migrationBlock: { migration, oldSchemaVersion in
// We haven’t migrated anything yet, so oldSchemaVersion == 0
if (oldSchemaVersion < 1) {
// Nothing to do!
// Realm will automatically detect new properties and removed properties
// And will update the schema on disk automatically
}
})
// Tell Realm to use this new configuration object for the default Realm
Realm.Configuration.defaultConfiguration = config
and then it says to use let realm = try! Realm() to get the realm instance. However, in our application we are using our own realm configurations with something like
let realm = try! Realm(configuration: RealmConfig.getConfig(typeURL: .userData)!)
We have a few different configurations besides .userData. My question is, how does one go about doing migrations with these non-default configurations? The code example really only shows how to set the default configuration which is insignificant for my use. I couldn't find anything like
Realm.Configuration.userData = config
Does something like this exist that I am missing? Or is there another way I'm supposed to go about this?
You can instantiate different Realm instances with different configurations like this:
let userDataConfiguration = Realm.Configuration(...)
let userDataRealm = try! Realm(configuration: userDataConfiguration)
Learn more in docs at https://realm.io/docs/swift/latest/#realms
I have created an Amazon Web Services EC2 instance and deploy one of the AMIs with a Realm Object Server as its documentation explains:
https://realm.io/docs/realm-object-server/#install-realm-object-server
Once installed and created my admin user, I have completed the iOS tutorial: https://realm.io/docs/tutorials/realmtasks/, just until point 7, enough for creating task, but when I add new task in app, nothing happens. Debugging, I notice that next sentence try, is not executing:
let items = self.items
try! items.realm?.write {
items.insert(Task(value: ["text": text]), at: items.filter("completed = false").count)
}
The items collection seems to be initialized properly:
In the ROS dashboard, can see the database referenced in Xcode:
In image can be see "Default permissions" property is no access, is this the reason of not creating new task? If so, how can I change that permissions? If that is not the reason, anyone could help me?
thanks in advance
The problem was that I did not follow al the complete tutorial because I do not want to use the desktop application, just mobile example, but realm init objects in desktop app, so I never got a valid realm where perform actions.
For a quick and simple start with this realm tutorial pointing to an online server, not local, you must initialize the TaskList object and add it to self.realm on setup
// Show initial tasks
func updateList() {
if self.realm.objects(TaskList.self).count == 0 {
let list = TaskList()
list.id = "000001"
list.text = "lista de prueba"
// Add to the Realm inside a transaction
try! self.realm.write {
self.realm.add(list)
}
}
if self.items.realm == nil, let list = self.realm.objects(TaskList.self).first {
self.items = list.items
}
self.tableView.reloadData()
}
checking if there is not a TaskList with if self.realm.objects(TaskList.self).count == 0 {, you can create one and init realm.
You probably forgot to launch Mac demo app first or login with a different user. The tutorial assumes that existing data will be synced at login. If you have never launched the Mac app or logged in a different user, it may happen that items are not managed by Realm.
The tutorial says the following:
First, please follow the Get Started instructions to get set up with the Realm Mobile Platform and to launch the macOS version of RealmTasks.
Also, you attempt to try this tutorial with ROS on AWS. The tutorial assumes running ROS on a same local machine.
So you should modify the Mac app code to connect to the AWS, then run it to synchronize the initial data. Then run the tutorial iOS app.
The default permissions here show whether all other users can access the Realm or not, which isn't the case here. We already have an internal issue around clarifying this.
The registered user who owns the Realm has individual permissions to it by default. If you wouldn't have permissions opening the synchronized Realm from the client would also fail because of insufficient permissions, so this isn't the problem here.
So going back to your code:
try! items.realm?.write { … }
My guess would be that the problem here is that the collection isn't already attached to a Realm, so that items.realm? evaluates to null. In that case the write transaction wouldn't be executed.
You can resolve this by making sure to add the items first to a Realm or executing the write directly on a synchronized Realm.