I am using an Android tablet with a Xamarin/C# application. With this tablet I am trying to access an SQLite database that resides on my Windows 10 machine. I opted to use the USB/Android vs the Android emulator, and the application still resides on the Windows 10 machine. It seems irrelevant, but I've also tried mapping a drive, sharing the folder, and creating a network connection. Project References
This is the code:
using Microsoft.Data.Sqlite;
using System;
using System.Windows.Input;
using Xamarin.Essentials;
using Xamarin.Forms;
namespace CicoAndroid
{
public partial class MainPage : ContentPage
{
public ICommand TapCommand => new Command(async (url) => await Launcher.OpenAsync(url));
private readonly string db1 = #"Data Source=\LAPTOP-FJUIC9RR\db\db.sqlite";
public MainPage()
{
InitializeComponent();
}
private void LoginClicked(object sender, EventArgs e)
{
int rows;
try
{
Console.WriteLine("DB1: " + db1);
SqliteConnection conn = new SqliteConnection(db1);
conn.Open(); ***This is the line that is throwing the exception.***
using (SqliteCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "SELECT COUNT(*) FROM [tblUsers] WHERE USERNAME = 'someUser'";
rows = (int)cmd.ExecuteScalar();
Console.WriteLine("ROWS: " + rows);
cmd.Dispose();
}
conn.Dispose();
}
catch (Exception ex)
{
lblAuth.Text = "FUL: a.c.us" + Environment.NewLine + ex.ToString();
return;
}
I am very very new to Xamarin and C#, and I've tried tens of variations with the code and NuGet SQLite packages. Any help will be greatly appreciated.
Thank you
Xamarin.Forms supports database-driven applications using the SQLite database engine, which makes it possible to load and save objects in shared code.
Article Xamarin.Forms Local Databases describes how Xamarin.Forms applications can read and write data to a local SQLite database using SQLite.Net.
Integrate SQLite.NET into mobile apps by following these steps:
Install the NuGet package.
Configure constants.
Create a database access class.
Access data in Xamarin.Forms.
Advanced configuration.
For more details, you can check document:
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/data-cloud/data/databases .
And there is also a sample included in above links, you can check and refer to it's code.
Besides, you can also check document Store data in a local SQLite.NET database.
I want to save my logs to a folder which I can access with windows explorer. For example I want to create my log in the following path
This PC\Galaxy A5 (2017)\Phone\Android\data\MyApp\files
So I tried to use Environment variables... I get such as
/data/user/...
But here i cannot see the file what I created (using code I can access the path but I want to see in the explorer).
how I can create a path like above with code?
When I tried this code
var finalPath2 = Android.OS.Environment.GetExternalStoragePublicDirectory
(Android.OS.Environment.DataDirectory.AbsolutePath);
I get the path "/storage/emulated/0/data"
and
If i use the code
var logDirectory =Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.ApplicationData),"logs");
I get the following path like:
/data/user/0/MyApp/files/.config/logs
and
var logDirectory =Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.MyDocuments),"logs");
"/data/user/0/IM.OneApp.Presentation.Android/files/logs"
but unfortunately I cannot access this folder by explorer....
This PC\Galaxy A5 (2017)\Phone\Android\data\MyApp\files
So how to find out this path in c# by using environments?
Update:
when I give the following path hardcoded, it creates the file where I want..
logDirectory = "/storage/emulated/0/Android/data/MyApp/files/logs";
is there any environment to create this path? I can combine 2 environments and do some string processing in order to create this path. But maybe there is an easier way?
You are looking for the root of GetExternalFilesDir, just pass a null:
Example:
var externalAppPathNoSec = GetExternalFilesDir(string.Empty).Path;
Note: This is a Context-based instance method, you can access it via the Android application context, an Activity, etc... (see the link below to the Android Context docs)
Shared storage may not always be available, since removable media can be ejected by the user. Media state can be checked using Environment.getExternalStorageState(File).
There is no security enforced with these files. For example, any application holding Manifest.permission.WRITE_EXTERNAL_STORAGE can write to these files.
re: https://developer.android.com/reference/android/content/Context#getExternalFilesDir(java.lang.String)
string docFolder = Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.MyDocuments), "logs");
string libFolder = Path.Combine(docFolder, "/storage/emulated/0/Android/data/MyApp/files/logs");
if (!Directory.Exists(libFolder))
{
Directory.CreateDirectory(libFolder);
}
string destinationDatabasePath = Path.Combine(libFolder, "temp.db3");
db.Backup( destinationDatabasePath, "main");
I have been following this tutorial in its entirety, on how to store data in a local database. On iOS everything works fine, unfortunately on android i get an exception upon creating a table in my database file. The method for creating the table is:
public CalcDatabase(string dbPath)
{
database = new SQLiteAsyncConnection(dbPath);
database.CreateTableAsync<Calculation>().Wait();
}
And my custom class for getting the database path on Android is as follows:
public class LocalFileHelper : IFileHelper
{
public string GetLocalFilePath(string filename)
{
var path = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
path = Path.Combine(path, filename);
if(!Directory.Exists(path))
{
Directory.CreateDirectory(path);
}
return path;
}
}
This is the error that im getting from SQLite:
Could not open database file: /data/user/0/com.companyname.XX/files/Calculation.db3 (CannotOpen)
I have tried targeting several different APIs, I have tried to clean and rebuild my solution, and I have tried to reinstall the SQLite-net-pcl NuGet packages across the whole solution. Nothing works.
I have read, that it has to do with permissions, still, I do however find it strange that the official Microsoft tutorial doesn't cover this if it was a thing.
You need to check out the Android Permissions declaration (and grants) for Write and Read to external storage on your device or emulator.
It must be enough.
Make sure to delete bin and obj folders, clean and rebuild solution to get rid of any cached data on app compilation.
I am in the process of implementing access to a SQLite database via SQLCipher in my hybrid Cordova app for Android which uses one custom plugin (i.e. written by me). The SQLCipher documentation - as well as other tutorials on using SQLite in Android - keep referring to Context.getDatabasePath. In my plugin code I store other app files and make extensive use of Context.getFilesDir. In what way is getDatabasePath different from getFilesDir. For instance, does it promise a better chance that the database will persist and not somehow get dumped because the OS decides to create "some more room" by deleting some files stored in Context.getFilesDir?
Both are resolved to the same directory. getDatabasePath calls getDatabasesDir.
getDatabasesDir:
private File getDatabasesDir() {
synchronized (mSync) {
if (mDatabasesDir == null) {
if ("android".equals(getPackageName())) {
mDatabasesDir = new File("/data/system");
} else {
mDatabasesDir = new File(getDataDir(), "databases");
}
}
return ensurePrivateDirExists(mDatabasesDir);
}
}
getFilesDir:
#Override
public File getFilesDir() {
synchronized (mSync) {
if (mFilesDir == null) {
mFilesDir = new File(getDataDir(), "files");
}
return ensurePrivateDirExists(mFilesDir);
}
}
Notice the returned File is resolved by ensurePrivateDirExists in both method, which has the same input directory resolved by getDataDir.
getDataDir
Returns the absolute path to the directory on the filesystem where all
private files belonging to this app are stored.
So, there is NO difference in your case.
Do not forget the returned path can change, as the doc says:
The returned path may change over time if the calling app is moved to
an adopted storage device, so only relative paths should be persisted.
I've created a sqlite database programmatically with the default way of extending SQLiteOpenHelper and overriding onCreate(). This way the db gets created on the fly when needed.
I'd like to check the contents of the db file on my OS X machine with a sqlite browser.
I know the name of the db file, but I can't find it on the device. I've connected to the device via USB and looked with finder and terminal, but I just can't find the db file.
What is the default location for a sqlite databases on an android device?
You can find your created database, named <your-database-name>
in
//data/data/<Your-Application-Package-Name>/databases/<your-database-name>
Pull it out using File explorer and rename it to have .db3 extension to use it in SQLiteExplorer
Use File explorer of DDMS to navigate to emulator directory.
For this, what I did is
File f=new File("/data/data/your.app.package/databases/your_db.db3");
FileInputStream fis=null;
FileOutputStream fos=null;
try
{
fis=new FileInputStream(f);
fos=new FileOutputStream("/mnt/sdcard/db_dump.db");
while(true)
{
int i=fis.read();
if(i!=-1)
{fos.write(i);}
else
{break;}
}
fos.flush();
Toast.makeText(this, "DB dump OK", Toast.LENGTH_LONG).show();
}
catch(Exception e)
{
e.printStackTrace();
Toast.makeText(this, "DB dump ERROR", Toast.LENGTH_LONG).show();
}
finally
{
try
{
fos.close();
fis.close();
}
catch(IOException ioe)
{}
}
And to do this, your app must have permission to access SD card, add following setting to your manifest.xml
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Not a brilliant way, but works.
The Context contains many path functions: Context.getXXXPath()
One of them is android.content.Context.getDatabasePath(String dbname) that returns the absolute path of a database called dbname.
Context ctx = this; // for Activity, or Service. Otherwise simply get the context.
String dbname = "mydb.db";
Path dbpath = ctx.getDatabasePath(dbname);
The returned path, in this case, would be something like:
/data/data/com.me.myapp/databases/mydb.db
Note that this path is autogenerated if using SQLiteOpenHelper to open the DB.
If you're talking about real device /data/data/<application-package-name> is unaccessible. You must have root rights...
This is and old question, but answering may help others.
Default path where Android saves databases can not be accesed on non-rooted devices. So, the easiest way to access to database file (only for debugging environments) is to modify the constructor of the class:
public class MySQLiteOpenHelper extends SQLiteOpenHelper {
MySQLiteOpenHelper(Context context) {
super(context, "/mnt/sdcard/database_name.db", null, 0);
}
}
Remember to change for production environments with these lines:
public class MySQLiteOpenHelper extends SQLiteOpenHelper {
MySQLiteOpenHelper(Context context) {
super(context, "database_name.db", null, 0);
}
}
/data/data/packagename/databases/
ie
/data/data/com.example.program/databases/
A SQLite database is just a file. You can take that file, move it around, and even copy it to another system (for example, from your phone to your workstation), and it will work fine. Android stores the file in the /data/data/packagename/databases/ directory. You can use the adb command or the File Explorer view in Eclipse (Window > Show View > Other... > Android > File Explorer) to view, move, or delete it.
well this might be late but it will help.
You can access the database without rooting your device through adb
start the adb using cmd and type the following commands
-run-as com.your.package
-shell#android:/data/data/com.your.package $ ls
cache
databases
lib
shared_prefs
Now you can open from here on.
If you name your db as a file without giving a path then most common way to get its folder is like:
final File dbFile = new File(getFilesDir().getParent()+"/databases/"+DBAdapter.DATABASE_NAME);
where DBAdapter.DATABASE_NAME is just a String like "mydatabase.db".Context.getFilesDir() returns path for app's files like: /data/data/<your.app.packagename>/files/ thats why you need to .getParent()+"/databases/", to remove "files" and add "databases" instead.
BTW Eclipse will warn you about hardcoded "data/data/" string but not in this case.
By Default it stores to:
String DATABASE_PATH = "/data/data/" + PACKAGE_NAME + "/databases/" + DATABASE_NAME;
Where:
String DATABASE_NAME = "your_dbname";
String PACKAGE_NAME = "com.example.your_app_name";
And check whether your database is stored to Device Storage. If So, You have to use permission in Manifest.xml :
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
You can access it using adb shell how-to
Content from above link:
Tutorial : How to access a Android database by using a command line.
When your start dealing with a database in your program, it is really
important and useful to be able to access it directly, outside your
program, to check what the program has just done, and to debug.
And it is important also on Android.
Here is how to do that :
1) Launch the emulator (or connect your real device to your PC ). I
usually launch one of my program from Eclipse for this. 2) Launch a
command prompt in the android tools directory. 3) type adb shell. This
will launch an unix shell on your emulator / connected device. 4) go
to the directory where your database is : cd data/data here you have
the list of all the applications on your device Go in your application
directory ( beware, Unix is case sensitive !! ) cd
com.alocaly.LetterGame and descend in your databases directory : cd
databases Here you can find all your databases. In my case, there is
only one ( now ) : SCORE_DB 5) Launch sqlite on the database you want
to check / change : sqlite3 SCORE_DB From here, you can check what
tables are present : .tables 6) enter any SQL instruction you want :
select * from Score;
This is quite simple, but every time I need it, I don't know where to
find it.
Do not hardcode path like //data/data/<Your-Application-Package-Name>/databases/<your-database-name>. Well it does work in most cases, but this one is not working in devices where device can support multiple users. The path can be like //data/user/10/<Your-Application-Package-Name>/databases/<your-database-name>. Possible solution to this is using context.getDatabasePath(<your-database-name>).
If your application creates a database, this database is by default saved in the directory DATA/data/APP_NAME/databases/FILENAME.
The parts of the above directory are constructed based on the following rules. DATA is the path which the Environment.getDataDirectory() method returns. APP_NAME is your application name. FILENAME is the name you specify in your application code for the database.
You can find your database file :
Context.getDatabasePath(getDatabaseName())
getDatabaseName from class SQLiteOpenHelper
In kotlin you can find it in this way:
val data: File = Environment.getDataDirectory()
val currentDBPath = "//data//$packageName//databases//"
val destDir = File(data, currentDBPath)
You can also check whether your IDE has a utility like Eclipse's DDMS perspective which allows you to browse through the directory and/or copy files to and from the Emulator or a rooted device.
Define your database name like :
private static final String DATABASE_NAME = "/mnt/sdcard/hri_database.db";
And you can see your database in :
storage/sdcard0/yourdatabasename.db
public class MySQLiteOpenHelper extends SQLiteOpenHelper {
MySQLiteOpenHelper(Context context) {
super(context, "/mnt/sdcard/database_name.db", null, 0);
} }
Do not hardcode "/sdcard/"; use Environment.getExternalStorageDirectory().getPath() instead
#Shardul's answer is correct.
Besides that, new Android Studio has a tool called: App Inspection, which you can view database directly.
Here is the version of Android Studio:
Android Studio Arctic Fox | 2020.3.1 Patch 3
Build #AI-203.7717.56.2031.7784292, built on October 1, 2021