I've found a lot of solutions to about how its possible to copy a database from assets to /data/data/tld.c.u/databases/ - But is it absolutely impossible to just open the database in readonly and query its content?
I have a rather large database i'm distributing with the app and its kind of a waste if the database must be copied out of the assets folder.
But is it absolutely impossible to just open the database in readonly and query its content?
Yes.
I have a rather large database i'm distributing with the app and its kind of a waste if the database must be copied out of the assets folder.
Consider not distributing it with the app, but rather downloading it on first run, or using Google Play's new APK expansion files facility.
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In my iOS app I have a large (270MB), pre-populated, read-only sqlite database. I keep the data in the app bundle and query it with no problems. I do not copy the database to the user's documents folder, because it would be pointless in this situation to take up more space with a duplicate database. I have a separate much smaller database I copy to the user's documents folder to store the user's preferences. The app works just fine.
Now I'm trying to port my app to Android using Android Studio, but it does not seem possible to access the database from the assets folder. I have found plenty of documentation on database helper classes for Android, which I have tried, but the approach always seems to be to copy the database from the assets folder to the user's data folder. This would be a waste of space and also in my experience the app is unable to copy the database without crashing (maybe because of the size? I had no problems copying a smaller test database).
Is there a way to access the database without copying it to the user's data folder? If not can anyone think of another way of approaching this?
No, You can not directly write into the files of ASSETS folder in your application as the resources folders are read-only.
So You have to compulsory copy your database first from your assets folder to your sdcard and then only you will be able to read & write into it.
As GrIsHu said, you can only read database from asset folder. If you need to do more operation like create, update, delete you can do a tricks. Copy the database from assets folder to storage and then you can do anything you want.
Here is a quick example of Working with Android Pre Built Database.
There is a easy to use library too for accessing database from assets folder. You can check [Android SQLiteAssetHelper] here.2 Good luck!
I am developing an app in android which consists of activities that need to connect to the Database . I added my database file in assets folder which gets copied over to applications database directory on first time the app runs but "assets" directory and "data" directory(on rooted devices) can be accessed by any other application . I'm confusing between using database file or create database in code . If i create database in code it make the database file disappear in the "assets" folder . When users change the file extension from .apk to .zip ,database file will not appear in assest folder . What I should to do ?
Please give me some advice !
Both ways are good and useful it completely depends on your need.
By creating database in code you can secure your data from other applications but it will take so much pain to create it in that way so i suggest you to use a db or sqlite file in assets folder and while copying database on device or data folder use some security parameters to encrypt it or you can hide your app database folder on device so other applications and users will be not able to access it easily.
Well keeping Database in assets folder is not at all a bad practice plus it saves coding of creating a database , as far as you want to make it secure you have to do 2 things
1.keep you database in assests folder , and copy and save it in the internal memory , now its available only to your application and delete it from assests folder .
2.Use Proguard to protect it from somebody decompiling your application and obtaining the assests.
And yea if its a confidential data in the application and your application is worth it then you can also go for "encrypting data" but yea its a TDS task , see for yourself what suits you now.
Honestly, this is the best explained and a very complete tutorial on the subject
SQLite Android Tutorial
Don't get repulsive, because it's a bit longer one. Everything is explained nicely and you don't have to do the thinking about the location of your asset folder on different devices and so on...
I'm looking to packing a large sqlite database with an android app, about 200-300MB. From what I've read, my options are putting it in the assets folder, and coping it out at runtime, resulting in duplicate data, or downloading the database from the web at runtime. I don't want to create a webserver for this app, so I was thinking of creating a seperate app that just installs the database to get around the data duplication problem.
All of those are pretty crummy, and I was wondering if there is a better solution?
First, I don't think you are allowed to put a 200-300MB database in your assets folder and distribute it as a single apk, since the hard limit for an apk file size is (as per google's documentation) 50 MB and I doubt that your db will compress that far.. Google introduced the "APK expansion files" for packaging large files with your apk. You can read all about those here: http://developer.android.com/google/play/expansion-files.html
I think (but I have no experience with expansion files myself) that this will not fix the issue you mentioned about having to deal with duplicate data because of the requirement to copy out your database file, but at least this will help you in the sense that you won't have to host your database file on your own webserver. I quickly scanned the documentation on the link I gave above and it clearly states that you should NOT throw away the expansion files when you are done with them, so no help on that part.
Of course, for the "setting up your own webserver part": I wouldn't even bother setting up my own webserver. There are plenty of parties out there that provide you some file hosting service. Probably you will have to pay for the bandwidth, but hey.. if people download your db file a lot, that also means that your app is doing well ;-)
I test of apk expansion files. I created a test app with a 100 MB sqlite database, uploaded the apk and database to the play store. I then downloaded the app onto the phone, the database was downloaded at the same time. The database was automatically renamed and placed in the publicly accessible directory:
/storage/sdcard0/Android/obb/com.example.app/main.1.com.example.app.obb
The app was able to open the database without any problems, but required external read and write permissions. The new and original database are bit for bit, the same. This appears to be the best solution for my use case.
A few issues, the new android developer console does not support uploading expansion files, so the old one needs to be used. Google only allows 2 expansion files, so that may be an issue for some use cases. Google say that you must not rename or delete the file, and that your app must be able to download the file from Google itself if it wasn't automatically installed.
I was having an SQLite database with size less than 1 MB in the asset folder. I am copying this database to the applications default database folder on application launch. It was working fine. Now the database has grown and due to limitations with the Asset folder, I am not able to copy the database from Asset folder to the application.
Is there any way to manage multiple databases in application? If yes, what will be the methods to query them separately? Please share some good link for such database queries.
Change your db file's suffix to media file type, such like yourdb.mpg . then you won't be limited by 1mb size, and you can copy it to data/your.packge/database folder when your app first run.
I am working on a library app and have books stored as .sqlite files. Each book's sqlite database file is about 10MB in size. I first tried to put it in assets folder and then copying it to database/ folder but since the file is >1Mb this gives me an IOException. Then I tried to access it from raw folder but its still giving me IOException. So, what is the correct way to access such a file. Also, in future the app might need to download such files from server, so in that case where should I store such database files?
Thanks!!
Before Android 3.0 you are not allowed to open files larger than 1mb.
From the link: [P]rior to Android 2.3, any compressed asset file with an uncompressed size of over 1 MB cannot be read from the APK.
Here are some solutions:
Perhaps you want to look into shrinking the size of the databases, and that might be by making your own, or by removing some of the entries that you do not need/want.
Another solution would be to offload the databases to a server that you have access to and require the application to access the web to get the data that is necessary from this server. I can imagine a nice RESTful API to do this.
There is a workaround to this issue. The limitation of 1MB is only for SQLite files and not for other file types. Rename your SQLite file as something like "db.mp3" and then when your app starts, you can copy this file to your SD Card and use it as a normal SQLite file from SD card.
I have implemented this solution and it works perfectly fine on all Android versions.
Have the app download the database from a web server to the sdcard - this saves the waste of storing both a compressed version in the .apk and an uncompressed version outside. And it's not really any more insecure as an .apk is just a zip file anyone who really wants to can read.