RoomDatabase

public RoomDatabase()

You cannot create an instance of a database, instead, you should acquire it via #Room.databaseBuilder or #Room.inMemoryDatabaseBuilder.

public void beginTransaction()

Wrapper for SupportSQLiteDatabase.beginTransaction.

@WorkerThread
public abstract void clearAllTables()

Deletes all rows from all the tables that are registered to this database as Database.entities.

This does NOT reset the auto-increment value generated by PrimaryKey.autoGenerate.

After deleting the rows, Room will set a WAL checkpoint and run VACUUM. This means that the data is completely erased. The space will be reclaimed by the system if the amount surpasses the threshold of database file size.

See SQLite documentation for details. FileFormat

public void close()

Closes the database.

Once a RoomDatabase is closed it should no longer be used.

public @NonNull SupportSQLiteStatement compileStatement(@NonNull String sql)

Wrapper for SupportSQLiteDatabase.compileStatement.

public void endTransaction()

Wrapper for SupportSQLiteDatabase.endTransaction.

public @NonNull InvalidationTracker getInvalidationTracker()

The invalidation tracker for this database.

You can use the invalidation tracker to get notified when certain tables in the database are modified.

public @NonNull SupportSQLiteOpenHelper getOpenHelper()

The SQLite open helper used by this database.

public @NonNull Executor getQueryExecutor()

The Executor in use by this database for async queries.

public @NonNull Executor getTransactionExecutor()

The Executor in use by this database for async transactions.

public T <T extends Object> getTypeConverter(@NonNull Class<@NonNull T> klass)

Gets the instance of the given Type Converter.

public boolean inTransaction()

Wrapper for SupportSQLiteDatabase.inTransaction. Returns true if current thread is in a transaction.

@CallSuper
public void init(@NonNull DatabaseConfiguration configuration)

Called by Room when it is initialized.

public boolean isOpen()

True if database connection is open and initialized.

When Room is configured with RoomDatabase.Builder.setAutoCloseTimeout the database is considered open even if internally the connection has been closed, unless manually closed.

public @NonNull Cursor query(@NonNull String query, Object[] args)

Convenience method to query the database with arguments.

public @NonNull Cursor query(@NonNull SupportSQLiteQuery query, CancellationSignal signal)

Wrapper for SupportSQLiteDatabase.query.

public @NonNull V <V extends Object> runInTransaction(@NonNull Callable<@NonNull V> body)

Executes the specified Callable in a database transaction. The transaction will be marked as successful unless an exception is thrown in the Callable.

Room will only perform at most one transaction at a time.

If a SQLiteDriver is configured with this database, then it is best to use useWriterConnection along with immediateTransaction to perform transactional operations.

public void runInTransaction(@NonNull Runnable body)

Executes the specified Runnable in a database transaction. The transaction will be marked as successful unless an exception is thrown in the Runnable.

Room will only perform at most one transaction at a time.

If a SQLiteDriver is configured with this database, then it is best to use useWriterConnection along with immediateTransaction to perform transactional operations.

public void setTransactionSuccessful()

Wrapper for SupportSQLiteDatabase.setTransactionSuccessful.

protected abstract @NonNull InvalidationTracker createInvalidationTracker()

Creates the invalidation tracker

An implementation of this function is generated by the Room processor. Note that this function is called when the RoomDatabase is initialized.

protected @NonNull SupportSQLiteOpenHelper createOpenHelper(@NonNull DatabaseConfiguration config)

Creates the open helper to access the database. Generated class already implements this method. Note that this method is called when the RoomDatabase is initialized.

protected void internalInitInvalidationTracker(@NonNull SupportSQLiteDatabase db)

Initialize invalidation tracker. Note that this method is called when the RoomDatabase is initialized and opens a database connection.

public final @NonNull Flow<@NonNull Set<@NonNull String>> RoomDatabaseKt.invalidationTrackerFlow(
    @NonNull RoomDatabase receiver,
    @NonNull String tables,
    boolean emitInitialState
)

Creates a Flow that listens for changes in the database via the InvalidationTracker and emits sets of the tables that were invalidated.

The Flow will emit at least one value, a set of all the tables registered for observation to kick-start the stream unless emitInitialState is set to false.

If one of the tables to observe does not exist in the database, this functions throws an IllegalArgumentException.

The returned Flow can be used to create a stream that reacts to changes in the database:

fun getArtistTours(from: Date, to: Date): Flow<Map<Artist, TourState>> {
  return db.invalidationTrackerFlow("Artist").map { _ ->
    val artists = artistsDao.getAllArtists()
    val tours = tourService.fetchStates(artists.map { it.id })
    associateTours(artists, tours, from, to)
  }
}