I'm just toying around with my schema and I can't get my app to load at all since I changed the schema/Entity class.
I have deleted the app on my testing devic, cleared the caches on AndroidStudio, and rebooted my machine but the error persists. All I did was change the default values of one of my Entity data classes for my Room database.
How do I force AndroidStudio to forget about the old table schema/Entity class without incrementing the version number and providing a migration path?
Error:
java.lang.IllegalStateException: Room cannot verify the data integrity. Looks like you've changed schema but forgot to update the version number. You can simply fix this by increasing the version number.
Android Studio doesn't save the database schema information, your app does. So you can clear the app data on your test device and will fix the problem without incrementing your version number.
However without clearing the app data, you can use RoomDatabase.Builder.fallbackToDestructiveMigration() along with incrementing the version number to avoid implementing migration logic if you're happy to lose the contents of the previous database.
You can try setting android:allowBackup to false in the manifest file.
Related
My app is getting the following error:
Room cannot verify the data integrity. Looks like you've changed schema but forgot to update the version number. You can simply fix this by increasing the version number.
I don't want to increase the version since the app I'm developing is not yet released. What should I do to prevent this error?
Just clear the app data after changing the schema.
If you do not care about the existing data in the Room DB, you can clear the tables like this:
viewModelScope.launch {
yourRoomDBInstance.clearAllTables()
}
Should I increment the value of the Room database version if I change the content of the database when its migration strategy is set to "fallback to destructive migration"?
Following changes made to database:
Some columns are removed.
Content of some rows is updated in the database file that is stored in assets.
Yes. You should update the version of the database even with fallback to destructive migration strategy. Room uniquely identifies every database version with an "identity hash string", which is kept in a configuration table.
Keeping the database version unchanged will cause the app to crash with an IllegalStateException. Internally Room checks the identity of the database comparing the identity hash of the current version vs the the one stored in the table called "room_master_table".
You can learn more about this in the below article which also explains in detail how to handle version change and testing.
Reference: https://medium.com/androiddevelopers/understanding-migrations-with-room-f01e04b07929
UPDATE: It is interesting that the app crashed in some users, but for some users including me, it didn't crash. So it's better to update the version of the database even though its migration strategy is fallback to destructive.
From my experience, it seems we don't have to increment the value of Room database version when its migration strategy is set to "fallback to destructive migration".
I changed the content of the database and removed some columns from the database file.
Then I installed the previous version of the app (unchanged database). Then I used the application and made sure a database instance is created.
Then I installed the new version of the app (changed database). And it didn't crash and everything worked fine. Changes applied to the database.
I want to update my app at play store with bug fixes. APP already uses Room DB. Do i need to migrate the DB. There is no change in the DB. There are only UI changes. Does new version effect the people DB, who are already using it. Can someone provide the details about this.
Thanks in advance.
There is no change in the DB.
The database remains and you do not need to change the version of the database (as per the #Database( .... version=?)).
You only need to change (increase) the database version if the schema has changed.
If you increase the version number and do not have a migration (migration class to call) to cover that version, then an IllegalStateException will occur unless you have .fallbackToDestructiveMigration() which WILL delete and recreate the database (effectively empty the database with the ne schema).
You can also use fallbackToDestructiveMigrationFrom()
It is the version number that determines if a database migration is required. However, if a change is made and if any of the entities mismatch the database when the .build method is run then an exception will result.
If you change an Entity (the schema) and do not increase the version number you will get an IllegalStateException with the message starting with Room cannot verify the data integrity. This is because the hash stored in the room_master_table has changed.
If you changed the database schema outside of room then you'd get an exception indicating that the expected schema (the database according to the Entities) does not match the schema found (the database according to the actual database).
In your situation I'd suggest not changing the version number.
You may wish to have a look at:-
Migrating Room Databases
#Database
fallbackToDestructiveMigration
fallbackToDestructiveMigrationFrom
i have the problem that when i release new version of my application, if i add a new column to one of my db tables, the database doesn't update. Any one know how to create a script of upgrade versione in case there are new columns or new tables??
Thanks
You have to remember that CreateTable it's already doing the columns update for you, because internally it calls a method called MigrateTable.
However you could have to handle more advanced modification to your database, like adding triggers or something similar.
In that case i suggest you to perform modifications manually.
In Xamarin Forms i've ended up with this:
https://gist.github.com/matpag/b2545cc22c8e22449cd7eaf6b4910396
Could not be the best strategy ever but seems to work for me.
Summarizing :
You have to save the database version in an internal flag of the SQlite database called user_version accessible with PRAGMA keyword.
Every time you get the database connection, you have to perform a check and see if the current database version is the same as the app last database version.
If not you need to perform a database update and set the new current version.
It's not a matter of a script, as there isn't such a thing. You can release a version with a "patch" that will run once, extracting all your records to a temporary form -> deleting the table -> creating it again (will assure it's created with the new columns and so on) -> reinserting the records again. After a while, when you know that all your users (or whenever you set the limit) have moved to the newer version you can just eliminate the "patch" from your code.
Hope it helps.
The automatic migration feature is still not working in sqlite.net-pcl, but it looks like it does work in the other sqlite package: sqlite-net-pcl, which is actually the Xamarin recommend sqlite package.
So I have an application on the market place. It's been running fine for several months. I've updated it twice with small bug fixes and made no change to the database what so ever.
Some of my users are getting the following error:
android.util.Log$TerribleFailure: Can t downgrade read-only database from version 2 to 1: /data/data/myapp/databases/MyAppDB
at android.util.Log.wtf(Log.java:275)
at android.util.Log.wtf(Log.java:254)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:129)
As I mentioned, there has been no change to the database if any of the updates. It obviously crashes when the getWriteableDatabase method is called. I'm stumped as to why this error is occurring.
My best guess is that the user's phone has no more space left and thus a writable database can't be openend and thus crashes the app.
Any ideas?
A sqlite database has a version number. The version number is set when you open the database.
For example, if you use SQLiteOpenHelper, the constructor has int version parameter.
The error you get happened because on the user's device there is an old database with version=2 set, but on your program update you are trying to open that old database requesting version=1. That's not allowed.
Just set the version on the updated program to 2 or more.