Component used: Room
Version used: 1.0.0-alpha1
Devices/Android versions reproduced on: n/a

A common scenario is where an app needs to ship a database as part of the APK, or downloaded on first run of the app. That might serve as starter data, or it might serve as a read-only database of reference information. For the packaged-in-the-APK scenario, Jeff Gilfelt's SQLiteAssetHelper is a common solution, which replaces SQLiteOpenHelper and transparently copies the database from assets into the proper spot in the filesystem before proceeding.

With Room, there is no obvious way to handle the pre-populated database scenario.

One possibility is that Room doesn't do anything, and we have to arrange to get the database in position prior to creating the RoomDatabase. However, for that to work, we need to know where to put the database. While we supply the database name, technically Room could be storing that database anywhere (e.g., in a room/ subdirectory off of the normal database directory on internal storage). If we are going to go this route, we need some sort of documented statement about where Room stores the database, or a method to retrieve that location (prior to creating the RoomDatabase), so we know where to copy the database file into.

Other possibilities include:

- Having the option of subclassing the Framework implementation of SupportSQLiteOpenHelper, so we can craft a SQLiteAssetHelper-style implementation. Right now, that class is not part of the public API. While we could fork all of the Framework stuff to try to get this, that seems like overkill.

- Having a createFromAsset() and/or createFromFile() method on RoomDatabase.Builder, for us to provide the location of the starter database, for Room to copy into position for us if the database does not already exist.

Thanks!