Technologies used for the app: Ionic, Capacitor, Angular and SQLite
The requirement is to use a prepopulated SQLite database in the app. The methods that I found over the internet across various blogs and forums mentioned running a SQL script to initialize the DB as a pre-population step, but this brings about an unwanted overhead time to start querying the DB. As in the user needs to wait for a minute or so for the SQL Script to run completely every time, even if the app exists.
This issue became a roadblock because when the need became to port a large-sized database, it was no longer feasible to write SQL scripts as the overhead time increased drastically. Also, a bigger problem is, in Android studio, Java started throwing Heap Memory exceeded error.
A solution that I tried was to port the database directly as an asset of the app so that it can be shipped along with the app. But, while placing the database file in src/assets/, every build of the app generates www/ to create a web app that can be wrapped in a native view. The builder and compiler delete all the contents of the previous build in the www/ folder, we must understand that the capacitor looks for the database file at www/ and not in www/assets/, but we can't place the database file at www/ as it gets deleted on every build.
Link to existing issue on using the sqlite extension
maybe my experience can help you
RULES FOR DEVELOPMENT
1
database1 of bundle ( Android APK) from /assets must be static and not for update. because they can be changed when the application will be reinstalled on you version
2
you must to create new database2 - local , on the device , programmatically - to store a user's data. you can affill this database2 with data from database1
3
when you will install new version of application: database1 one may be changed, but the database2 becomes constant
the same situation is in browser: programmatically created database not disappear from session to session.
I check - it works in my application...
Related
I have an Android app where I use a SQLIte DataBase. I am using the app and the DB is already big. Now I want to give this app with its DB to my coworkers. Where and How to put the DB for release? I have the DB in my phone but I need it in assets folder. I was trying but it doesn't work. I tried to copy the DB directly however I read that Android compress files in that folder. Please, any solution, thank you in advance.
http://blog.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/
Visit this link. It contains the easiest and well described answer for your question.
You can use emulator Like GenyMotion and any other emulator. Run your app on emulator then just go to Android Studio->Tools->Android Device Monitor Then select the emulator and in the file Explorer you can find your db file . and then export from the device and export to your desktop. here you can give it to any one.
You can use your own SQLite database by adding it to assets folder. The best way is to use Android SQLiteAssetHelper. Better than reinventing the wheel.
Here the excerpts from its readme:
An Android helper class to manage database creation and version
management using an application's raw asset files.
This class provides developers with a simple way to ship their Android
app with an existing SQLite database (which may be pre-populated with
data) and to manage its initial creation and any upgrades required
with subsequent version releases.
It is implemented as an extension to SQLiteOpenHelper, providing an
efficient way for ContentProvider implementations to defer opening and
upgrading the database until first use.
Rather than implementing the onCreate() and onUpgrade() methods to
execute a bunch of SQL statements, developers simply include
appropriately named file assets in their project's assets directory.
These will include the initial SQLite database file for creation and
optionally any SQL upgrade scripts.
I am not new to Android or Java but very new to Databases. I have been practicing with SQLite in Android and have now become completely stuck.
I want to completely remove the current database that I have been using in my app and create a new one with more columns, different types of columns, and etc...
I have tried "context.deleteDatabase()" which appears to delete the database but then after that I uninstall the app and re-install it with the myDatabaseHandler java class file having all the new columns and changed added to the file.
The code compiles and runs fine until I try to add info to the database, I receive an error cannot find columns, the error refers specifically to the columns that I added.
Why does it seem that I cannot start over completely. It seems like the structure or schema of the database won't change.
So how do I eliminate any evidence of the databases that I was practicing and messing around with, and just start completely new? After all, thats what practice is, you don't know what you are doing and you learn by making mistakes. So now I need to completely wipe away the mistakes, not upgrade just to make alterations.
Upgrading the database seems to provide an avenue for achieving close to what I want, but ultimately is way more involved and confusing for what I need when I just need to start over with a freshly created databases that has more columns.
The SQLiteOpenHelper class goes to great care to keep the old database to allow you to upgrade it in place.
If you're not interested in the old data, just change the file name. Then it is guaranteed that there is no old version. (You still have to call deleteDatabase() to get rid of the old file, but now that call cannot conflict with any accesses to the new file.)
Using the ADB tools from the SDK/platform-tools folder can help to remove all data (including the database schema)
./adb.exe -s shell pm clear <your app's package name>
will remove all the data associated with your app. Then you install the new version of the app, it will use the new database schema.
I've been trying(for days now) to get an Android map app working. This app has to work offline and im only interested in displaying a small city, after seeing all of my choices and trying them all, it seems that Nutiteq is a great choice, specifically the offline MBTiles option. After setting everything up, and using a .mbtiles file downloaded using TileMill, i get the following error:
No such table android_metadata
The .mbtile file i downloaded doesn't have this table, and i can't find which class made this query(if anyone can explain why it's needed great!!!); i tried updating my .mbtile file with Navicat to add this table with the desired locale column with the en_US value, and now it gives the following log error message:
can't upgrade read-only database from version 0 to 1
My questions are:
Is there a way to bypass this whole android_metadata query? I mean, if it's not included on the .mbtile why is it needed afterwards?
If you don't recommend bypassing it, how to fix my second error with the upgraded database?
Thanks.
Are you trying to modify the database during the upgrade? If it's readonly, you probably can't modify it. You could create a new one, though, and copy the data from the old to the new.
We have developed an APK Application running on tablets. In this application we have created various csv files and by reading these csv files, the apk creates database(sqllite) files when running for the first time. This database file is used in the application in various dropdowns(masters in other keywords). I am facing a very serious issue in this. We have a csv file of around 12000 rows in it and because of this the apk takes around 1 hour for the first time. By first time, I meant when I install the apk on tablet and run it for the first time. This is becoming a very serious issue in my application and I need to resolve this. Can anyone give any idea how to overcome this.
You should try preprocess the SQL database using an Android emulator/device running a special version of your app, put the result DB in your release APK, and simply copy the DB over to the appropriate place during application's first run. The process of retrieving the DB from Android emulator/device can be found here.
Some of my users are reporting that they cannot correctly open sqlite databases created in Android using sqlite jdbc or other tools like sqlite browser (http://sourceforge.net/projects/sqlitebrowser/).
Here is an example database with the problem:
http://pocket-for-android.1047292.n5.nabble.com/Desktop-Version-Screenshots-Work-In-Progress-tp4383220p4456017.html
This sqlite db was created on a HTC Sensation, running Android 2.3.3 and Sense 3.0.
The exact problem is that if you look at the file in a text editor you can see a bunch of tables being created but if you try and run "select * from groups;" you will get an SQLException: file is encrypted or is not a database.
I have tried using "select sqlite_version;" to see if it is a versioning issue - the sqlite browser says 3.6.18.but different tools give me different version numbers... not sure what is going on with that.
I should also point out that my app copies the db directly from the device (/data/data/com.citc.wallet/databases/wallet.db) onto Dropbox.
Any help would be really appreciated.
The solution was that the zentus project is not working with the latest versions of SQLite.
Fortunately someone is keeping a fork maintained here: http://www.xerial.org/trac/Xerial/wiki/SQLiteJDBC
All I had to do was replace the jar with the xerial one and it all worked. Xerial sqlite jdbc is in my opinion the best way of connecting to SQLite in Java (I tried several of the libs).
I am also getting the same problem.
But once I have changed the database name it resolved.
So, just try it by creating new database