Android room database won't export all the data

I'm trying to setup Room database backup functionality. Problem is that sql database file doesn't contain latest set of data in the app once downloaded. It always misses some most recent records. Is there a proper way to export room database? P.S. I didn't face similar problems when handled my db with sqliteHelper, so I suppose it must have something to do with Room.

Way I'm doing it:

@Throws(IOException::class)
private fun copyAppDbToDownloadFolder(address: String) {
    val backupDB = File(address, "studioDb.db") 
    val currentDB = applicationContext.getDatabasePath(StudioDatabase.DB_NAME)
    if (currentDB.exists()) {
        val src = FileInputStream(currentDB).channel
        val dst = FileOutputStream(backupDB).channel
        dst.transferFrom(src, 0, src.size())
        src.close()
        dst.close()
    }
}

Upvotes: 12

Answers (5)

Josseling Ubeda

Reputation: 1

I had the same problem and I solved it by copying the 3 files that are generated. I work correctly. And the same is done to import.

copyDataFromOneToAnother(application.getDatabasePath(AppDatabase.DATABASE_NAME).absolutePath, Environment.getExternalStorageDirectory().toString() + "/DATABASE_NAME.db")
                    copyDataFromOneToAnother(application.getDatabasePath(AppDatabase.DATABASE_NAME).absolutePath + "-shm", Environment.getExternalStorageDirectory().toString() + "/DATABASE_NAME.db" + "-shm")
                    copyDataFromOneToAnother(application.getDatabasePath(AppDatabase.DATABASE_NAME).absolutePath + "-wal", Environment.getExternalStorageDirectory().toString() + "/DATABASE_NAME" + "-wal")

 private fun copyDataFromOneToAnother(fromPath: String, toPath: String) {
            val inStream = File(fromPath).inputStream()
            val outStream = FileOutputStream(toPath)

            inStream.use { input ->
                outStream.use { output ->
                    input.copyTo(output)
                }
            }
        }

Upvotes: 0

Anjana Chauhan

Reputation: 49

kotlin:This works for me

private fun exportDb() {
    val TABLE_NAME = "order_table"

    val exportDir = File(getExternalStorageDirectory(), "/CSV")// your path where you want save your file
    if (!exportDir.exists()) {
        exportDir.mkdirs()
    }

    val file = File(exportDir, "$TABLE_NAME.csv")


    try {
        file.createNewFile()
        val db: MenuItemsDatabase = MenuItemsDatabase.getDatabase(requireActivity())
        val csvWrite = CSVWriter(FileWriter(file))
        val curCSV: Cursor = db.query("SELECT * FROM order_table", null)
        csvWrite.writeNext(curCSV.getColumnNames())
        while (curCSV.moveToNext()) {
            //Which column you want to exprort
               val arrStr = arrayOfNulls<String>(curCSV.getColumnCount())
        
            for (i in 0 until curCSV.getColumnCount() - 1) arrStr[i] = curCSV.getString(i)
            csvWrite.writeNext(arrStr)
        }
        csvWrite.close()
        curCSV.close()
        Toast.makeText(context, "Exported", Toast.LENGTH_SHORT).show()

    } catch (sqlEx: java.lang.Exception) {
        //Log.e("Payment fragment", "Exported error", sqlEx)
        Toast.makeText(context, "Exported error", Toast.LENGTH_SHORT).show()
    }
}

Upvotes: 2

Ali Azaz Alam

Reputation: 1868

You need to use

JournalMode.TRUNCATE

in your AppDatabase.java:

private static AppDatabase sInstance;

public static AppDatabase getDatabase(final Context context) {
    if (sInstance == null) {
        synchronized (AppDatabase.class) {
            if (sInstance == null) {
                sInstance = Room.databaseBuilder(context, AppDatabase.class, DATABASE_NAME)
                        .setJournalMode(JournalMode.TRUNCATE)
                        .build();
            }
        }
    }
    return sInstance;
}

This method will not create db.bad and db.wal files that's creating hindrance in exporting room db.

For exporting the DB file:

Link: Exporting db with creating folder on daily basis

Upvotes: 14

Muzammil Husnain

Reputation: 1258

I had same issue. you don't need to copy wal (write ahead log file) it's a temporary file. According to documentation we need to close all connection to database before importing or exporting database. This solved my problem and now i have to copy only main database file.

Example of database class:

public abstract class AppDB extends RoomDatabase {    

    private static final Object sLock = new Object();

    private static AppDB INSTANCE;

    // create new database connection
    public static AppDB getInstance(final Context context) {
        synchronized (sLock) {
            if (INSTANCE == null) {
                INSTANCE = Room.databaseBuilder(context.getApplicationContext(), AppDB.class, "packagename")                    
                    .build();
                }
            return INSTANCE;
        }
    }

    // close database
    public static void destroyInstance(){
        if (INSTANCE.isOpen()) INSTANCE.close();
        INSTANCE = null;
    }
}

Upvotes: 6

Tuesday Four AM

Reputation: 1276

I've solved it. When exporting (saving) sql database which you handle with Room, you have to export(and later import) both - your_database.bd and your_database.wal files. Later is a journal and afaiu keeps latest records.

Upvotes: 3

Android room database won&#39;t export all the data

Answers (5)

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Android room database won't export all the data