I know there are a lot of similar questions and I hope not being repeating but I tried different things and I am still unable to fix the issue. I am developing an Android app that uses SQLite to store some data internally. I have been using this app in my own phone for a month and I added lot of data I do not want to lose, but at the same time I have been improving the app in my computer, but the improvements made me change some column names, adding some columns and tables. So, right now I want to update the app in my phone.
The previous version had the database set to 2 and the new one is 3. In addition, my app has the ability to create backups of the database just copying the file to the SDcard, and the ability to restore it by replacing the internal database file for one that the user selects from the sd card. Now the problem is that I did a backup of the database from the phone and I moved it to my computer to import it in the new version of the app running in an emulator to ensure the app can upgrade the database as expected before I install the new version on my phone. The problem is that onUpgrade for the SQLiteOpenHelper is never called. I did different trials but nothing is working. I can ensure the database from my phone has version 2 (I used sqliteadmin "PRAGMA user_version;" SQL query and answers 2) and my app looks for version 3. The app crashes as it is unable to find the new tables.
Here you have the code executed when importing a backup:
private boolean importDatabase(String path) {
String dbPath = mDbHelper.getDbPath();
mDbHelper.close();
boolean result = copyFile(path, dbPath);
if (result) {
mDbHelper = new DbHelper(this);
mDbHelper.getWritableDatabase().close();
}
return result;
}
I have to mention as well that when the user reaches the place to import/export the database in the new version, a new empty database with version 3 has been created as the app needs an active database from the stating activity. Then, when importing, this empty database file is replaced by the imported one. I wonder if there is any cached data I am missing to clean.
Could you give me some clues to understand why onUpgrade is never called in this scenario?
Related
This is my first time working on a Xamarin App and I am new to the app development world so I need some help figuring out this process.
Currently I run a php web service that generates some SQL files that I run in DB Browser and I get a database file which I then put into my Assets and Resources Folder. Using each platform's API I copy the database into a writable folder and use that to run my queries.
I followed this really helpful tutorial and it worked perfectly fine.
https://medium.com/#hameedkunkanoor/creating-a-sqlite-databse-and-storing-your-data-in-your-android-and-ios-application-in-xamarin-2ebaa79cdff0 .
After the "initial" setup I store a timestamp in a local table and and the next time the user opens the app I pass that timestamp and retrieve data that is older than that timestamp. The I update that timestamp and continue the process. That data is sent back in JSON format and make the updates to the tables.
My only concern is if a new version were to come out where I add a new table or a new column which is not present in the current version of my Database, how should I take care of those update Web Service calls? Is there a way of monitoring my DB version? I read somewhere where I could just ignore the new data that is not present already, like table or columns, but I'm not really sure how to do that.
I also saw that if I call CreateTable on my current tables I could potentially update them?
Also for future reference each time I develop a new app would I need to regenerate a new database file to store in the assets/resources folder? Is there a more automated process for this? Along with monitoring the version of my database?
Any Help/Tutorials/Suggestions would be greatly appreciated.
You have to remember that CreateTable it's already doing the columns update for you, because internally it calls a method called MigrateTable which you can see here for further clarification: https://github.com/praeclarum/sqlite-net/blob/master/src/SQLite.cs#L562.
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.
Reference here.
I am a beginner in android programming, I created an android app which uses an exist DB with DBFlow. At first time I inserted a temp data to database so I can test the app. When I finished building the app I inserted real data and copied the new database -which is similar to the old one except for the real data- to assets folder but I did not find the new data.
How can I reset the database or change the data.
After changing database you must remove previous version of app from your device and then install the app again. This should solve your problem.
I have a database that I built in SQLite browser, and it works fine. I launched an app with a prebuilt database and now I want to add more tables and data to that database.
I can get the app to launch the onUpgrade() method of the SQLiteOpenHelper. But the problem is, it's doing that EVERY time I use the helper.
I have it localized to, only on app launch, separating the upgrade command from the helper I used to retrieve data, but this is still a problem.
I have figured it out though, as I have been using the same database on my computer (the one that I'm editing) since version 1. So, whenever it writes the newer database onto the SD card it's showing version 1 even though I should be up to version 4 by now.
So, my question is, how can I manually edit the database version of the original database so that when it updates it isn't writing the old version number over the new one?
To manually update the version to 4 you execute the following SQL statement:
PRAGMA user_version = 4
Another way to change the version of your Sqlite Database. You can use DB Browser for SQLite:
Open the database file with "DB Browser for SQLite".
Change the "User Version" number to whatever number you want
Click the "Save" button
You can also set it via the setVersion SqlLiteDatabase method.
Source: http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#setVersion(int)
My app uses a preloaded and copied from /assets to data/data ( Ship an application with a database) db which is simply a single table of product data and is 'read only' as users do not save to the DB. If I add more products to the DB table I need to get this to existing users. If I update my app with the new DB will the update process delete the old DB that was copied from the assets dir to data/data thereby allowing the 'DBexists' check to fail on first running the updated version thus triggering copying of the new DB from /assets to data/data?
Short answer, yes, if you put the following snippet it the onUpgrade() method:
try {
copyDataBase("database.db");
} catch (IOException e) {
Log.w(TAG, e);
}
It may be worth deleting the db file in copyDataBase() before writing over it, just to make it less likely to corrupt.
NB: this uses the implementation as used in the accepted answer of the question you linked.
Off the top of my head the only thing I can think of is to slightly abuse the onUpgrade() method in your SQLiteOpenHelper implementation, and change the database by making a call to this with a new version number and having it do whatever you need it to do in that method.
Saying that, I don't really know much about the Android app update process, so this could be way off.
I added a table to a database that my application uses and wrote some code to work with that table. Everything worked fine for my on my phone and in the emulator, so I sent the update to the market.
This cause me to receive quite a few stack traces in the developers console cause by
android.database.sqlite.SQLiteException: no such table: flag
(flag is the new table).
This got me to wondering, are databases deleted when the application is updated? Presently in my application I am looking to see if the database exists, and if it does then I don't recreate it.
I didn't catch this before I sent out the update because I uninstalled the application before uploading the debug version.
I've since rolled out a quick update that has a try catch blocks around all accesses to the new table(which should have been there in the first place, I know, I know).
User data is not deleted, including databases.
Your DB has a version number. When you update your app, you advance the version number so that you can detect a present "old" DB.
This can be used to trigger a migration routine. In your case it should have added new table to the DB.
SQLiteOpenHelper is the answer.