Android Room database file is empty - .db, .db-shm, .db-wal - android

Using room in android for database. When I tried to see the data in sqlviewer then no tables found in database file
Myapp.db file is empty.
Data/data/packageName/databases/Myapp.db

Go to folder Data/data/packageName/databases/ There has to be three files .db, .db-shm, .db-wal, copy all three files to one location and then open your Myapp.db these two extra files are needed to open db file

in android studio 3.1.*
in tool window bar click on "Device File explorer" generally you can find this in bottom right corner of the screenn
open directory in data/data/your-application-package/databases
with new architecture 3 files is created in databases directory
your-database-name
your-database-name-shm
your-database-name-wal
you have to export all 3 in the same directory
then open first one file (that is with your-database-name only ) in any sqlite browser.
and now you can see all your data .......
your-database-name-shm
your-database-name-wal
these two extra files are needed to open db file
if you will open database file only, than you will not found any table in that file

Make sure your database is closed when you exit your app, which will ensure that all outstanding transactions are committed:
#Override
protected void onDestroy() {
super.onDestroy();
// close the primary database to ensure all the transactions are merged
MyAppDatabase.getInstance(getApplicationContext()).close();
}
Then you can copy the database off your device using the Device File Explorer in Android Studio (look under /data/data/<your app package name>/databases).
You are also able to force a WAL checkpoint instead of closing the database, but in my humble opinion this option is easier (unless you are trying to backup your database within the app programmatically or something like that) and closing databases is a good idea (even if it's not really mentioned in the Android Room documentation).
Read more about sqlite WAL here: https://www.sqlite.org/wal.html

I saved the whole folder and that's it, I could browse the table.

Once check your Database class,
#Database(entities = arrayOf(Test::class), version = 1, exportSchema = false)
abstract class MyDatabase:RoomDatabase() {
private var INSTANCE: MyDatabase? = null
abstract fun testDao(): TestDao
}
Here, MyDatabase is my Database class, Test is the table name and TestDao is the Dao class.

Related

opening database in raw folder & perform different read operation on it

Title-Android-read database in raw folder..
My raw folder contains a database 'abc' & abc database contains one table say- xyz
i want to open 'abc' database for fetching data in it..
i want to use something like
SQLiteDatabase db=SQLiteDatabase.openDatabase(path, factory, flags);
1) how to give path to access database?
2) i want to open table & perform operation
Cursor c=db.query("xyz",null,null,null,null,null);
Raw has no path: It is a resource, so you need to reference is as such
using getResources().
You should, at the first run, copy it to the
/data/data/YOUR_APP_FOLDER/databases/YOUR_DB.db
Follow this tutorial.
http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/
Copy your database file from /res/raw or /asset in /data/data/<application_package_name>/database/ directory and give path of that directory.
Now you can easily access your database file from /data/data//database/ directory..
Look at Ship an application with a database

Android - Does SQLite Database Exist? [duplicate]

This question already has answers here:
Query if Android database exists!
(7 answers)
Closed 7 years ago.
How can I quickly check if a database exists in Android?
(not a Table - the entire database)
Open your database and catch the SQLitException which will be thrown in case if database doesn't exist. Note that, you should not call the openOrCreateDatabase() method. See this post for details; Query if Android database exists!
My way to check to see if your database exists is to open a file handle on it and see if the file exists. from my experience using "openOrCreateDatabase()" function will not throw an error if the db doesn't exist. take a look a the name "Open OR Create Database". meaning if there's no db to open it'll just make a new one, so regardless of if there was one before there is one now. I think the only time you'll get an error thrown is if it can't do either. which from what the guy said I don't believe is what they are trying to test for, I think he wanted his program to know if the db was already there before hand, and not to automatically create a blank one if there wasn't. so Since all db's are stored as files, the first parameter in that open database command is the file name. So I think the best option is to check to see if the db file exists like so:
File dbtest = new File("/data/data/yourpackagename/databases/dbfilename");
//If you have Context, you could get the Database file using the following syntax
//File dbtest = getApplicationContext().getDatabasePath("dbfilename.db");
if(dbtest.exists())
{
// what to do if it does exist
}
else
{
// what to do if it doesn't exist
}

How to delete SQLite database from Android programmatically

I would like to delete the database file from the Android file system programatically? Can I have a shell script launch adb which in turns runs a shell script in the Android space to do the database deletion? Can I get this done from within a JUnit test case (with a system() call)?
How do I delete an entire database in Android? I need to make the whole thing go away so I can test database creation. I can drop tables, but that's not enough. This is in the emulator, not on a phone.
Once you have your Context and know the name of the database, use:
context.deleteDatabase(DATABASE_NAME);
When this line gets run, the database should be deleted.
The SQLiteDatabase.deleteDatabase(File file) static method was added in API 16. If you want to write apps that support older devices, how do you do this?
I tried: file.delete();
but it messes up SQLiteOpenHelper.
Thanks.
NEVER MIND! I later realized you are using Context.deleteDatabase(). The Context one works great and deletes the journal too. Works for me.
Also, I found I needed to call SQLiteOpenHelp.close() before doing the delete, so that I could then use LoaderManager to recreate it.
It's easy just type from your shell:
adb shell
cd /data/data
cd <your.application.java.package>
cd databases
su rm <your db name>.db
Try:
this.deleteDatabase(path);
or
context.deleteDatabase(path);
context.deleteDatabase("database_name.db");
This might help someone. You have to mention the extension otherwise, it will not work.
Also from Eclipse you can use DDMS which makes it really easy.
Just make sure your emulator is running, and then switch to DDMS perspective in Eclipse. You'll have full access to the File Explorer which will allow you to go in and easily delete the entire database.
context.deleteDatabase(DATABASE_NAME); will delete the database only if all the connections are closed. If you are maintaining singleton instance for handling your database helper - it is easy to close the opened Connection.
Incase the databasehelper is used in multiple place by instantiating directly, the deleteDatabase + killProcess will do the job even if some connections are open. This can be used if the application scenario doesn't have any issues in restarting the app.
Delete old Db when uninstall the app.
Setting android:allowBackup="false" in the application tag in AndroidManifest.xml fixed the problem. It seems that for some weird reason the Android OS was restoring from a backup every time I deployed the app.
you can create a file object of current database path and then delete it as we delete file from folder
File data = Environment.getDataDirectory();
String currentDBPath = "/data/com.example.demo/databases/" + DATABASE_NAME;
File currentDB = new File(data, currentDBPath);
boolean deleted = SQLiteDatabase.deleteDatabase(currentDB);
I used Android database delete method and database removed successfully
public bool DeleteDatabase()
{
var dbName = "TenderDb.db";
var documentDirectoryPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
var path = Path.Combine(documentDirectoryPath, dbName);
return Android.Database.Sqlite.SQLiteDatabase.DeleteDatabase(new Java.IO.File(path));
}
I have used the following for "formatting" the database on device after I have changed the structure of the database in assets. I simply uncomment the line in MainActivity when I wanted that the database is read from the assets again. This will reset the device database values and structure to mach with the preoccupied database in assets folder.
//database initialization. Uncomment to clear the database
//deleteDatabase("questions.db");
Next, I will implement a button that will run the deleteDatabase so that the user can reset its progress in the game.
If you are going to delete Table or Database , this way is worked:
1- Delete Table - It means keep Database but clean data from a table
* Just in DataHelper class add
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("delete from " + TABLE_NAME);
2- Delete Database - It means clean all records but keep file name
In the Activity
myDb = new DbHelper(this);
myDb.close();
myDb.delAll(getApplicationContext());
recreate();
In DataHelper class add
public void delAll(Context context) {
context.deleteDatabase(DB_NAME);
}
From Application Manager, you can delete whole application with data. Or just data by it self. This includes database.
Navigate to Settings. You can get to the settings menu either in
your apps menu or, on most phones, by pulling down the notification
drawer and tapping a button there.
Select the Apps submenu. On some phones this menu will have a
slightly different name such as Application Manager.
Swipe right to
the All apps list. Ignore the lists of Running and Downloaded apps.
You want the All apps list.
Select the app you wish to disable. A properties screen appears with
a button for Force Stop on the upper left and another for either
Disable or Uninstall updates on the upper right side.
Delete data.

How does android access a sqlite database included in the assets folder

I already have a SQLite database. I put it in the assets folder of my project. I read the Android documentation. It said that for all the databases in Android, the path is data/data/pack_name/database_name.
This confused me. I just placed it in the assets folder, so the path is data/data/assets/database_name?
The package name is not the project name, the package name is the namespace. From Anthony's link.
Remember to change the "YOUR_PACKAGE"
to your application package namespace
(i.e: com.examplename.myapp) in the
DB_PATH string.
For example, from the Hello World tutorial, the project name is HelloAndroid but the package name is com.example.helloandroid
If this application had a database, it would be stored at data/data/com.example.helloandroid/database
To see how it is for the other applications you can start your emulator. On the menu bar you have your avd's name (I think it stands for Android Virtual Device). On mine it s "avdessay:5554"
(On Linux) From command line, type:
adb -s emulator-5554 shell
You have to replace 5554 by whatever port you are using.
if you have the command prompt '#' you can type:
cd data/data
There, you will see that eveything is in a form of a package name.
More info here
When you create a database by utilizing the SQLiteDatabase or SQLiteOpenHelper classes, it creates the database in your data/data/package_name/database.
You can access that resource by using
InputStream myInput = myContext.getAssets().open(your_database_here);
Any other information, look at Using your own SQLite database in Android Applications
The package_name portion of the path, would be the name of your package. You can find the name of the package at the first line in your .java files.
As an example, my class starts with this at the top
package com.forloney.tracker;
So my database is in data/data/com.forloney.tracker/database folder.
Hope this makes sense.
#ScCrow I too followed this example and had the same problems you did until I realized I was not using the DataBaseHelper correctly (or rather it had a quirk I overlooked).
When you use your DatabaseHelper class in your activity, you have to make sure you call createDatabase first! If you look at the code for openDatabase it does NOT check to see if the database exists, so you either have to (attempt to) create the database in each activity you use it in, or modify the openDatabase method to check to make sure the db exists. The link posted does actually instruct you to use it this way but you (like me) may have glossed over that.
Bad:
DBAdapter db = new DBAdapter(this);
db.openDataBase(); //Bad! db not created yet!
Good:
DBAdapter db = new DBAdapter(this);
db.createDataBase(); //needs exception handling
db.openDataBase();
When I try to open my DB, I get "unable to open database file". I assume its not finding the DB and not some other programmer error. In the log I see the following which looks good to me.
sqllite3_open_v2("/data/data/com.isildo.HelloListView/databases/ListsDB" ...
This is the setup
private static String DB_PATH = "/data/data/com.isildo.HelloListView/databases/";
private static String DB_NAME = "ListsDB";
In my projects assets in the Package Explorer, I see the ListsDb database.
So I at least think I have it all correct. I am using the example at
[http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/]
In one of the posts here, someone offers a suggestion about setting some Assets parameters.
{no response to post there}
**To get an ASSETS folder into your APK:
In /nbproject/project.properties,
change assets.dir=
to
assets.dir=assets
assets.available=true
In /nbproject/build-impl.xml, there is line in the “if=assets.available” target that reads
that needs to be changed to**
Is this something we need to do, and if so, can we get a little better direction on the changes required. I could not find the places to make the suggested changes I looked at the project settings, and other things.
Yep, Im new to the environment, so I may just be not finding them. Im using Eclipse on windows.
In your DBAdapter.java, change the return type of openDatabase method to SQLiteDatabase.
When you access the database simply use SQLiteDatabase data = db.openDatabase(), where db is DBAdapter db = new DBAdapter(this).

How to access an existing sqlite database in Android?

So far we have developed apps in android that create database on runtime. We like to know how can we access a pre-built or existing database/sqlite file in our android app? Please provide detail
Take a look at the documentation for android.database.sqlite.SQLiteDatabase.
In particular, there's an openDatabase() command that will access a database given a file path.
SQLiteDatabase db = SQLiteDatabase.openDatabase(path, null, 0);
Just specify the path to your database as the path variable, and it should work.
I have followed the same road and found two issues:
Include the _id field on any table you create and make sure it is
part of the columns to return when you query any table.
You may run into an error like Failed to open the database. closing
it.. This is because we are copying the database from an existing
file instead of creating tables on top of a db created by the sqlite
android API and the table android_metadata may not exist. For
creating it just run the following query on your db:
CREATE TABLE android_metadata (locale TEXT);
And add the corresponding locale, for example en_US
First copy your SDCARD and give it's path in the variable "DBNAME" in the following example.
it will be something like "/sdcard/persons.db" if you are directly pulling it to sdcard.
Use this for accessing database in application :
Context context = getApplicationContext();
context.getDatabasePath(DataBaseHelper.database_Name);

Categories

Resources