room migration using existing boolean column types

SQLite does not have a boolean data type. Room maps it to an INTEGER column, mapping true to 1 and false to 0. I think below code would be work

database.execSQL("ALTER TABLE xyz_table ADD COLUMN abc INTEGER DEFAULT 0");

It is undocumented.

Define the migration for the new attribute newAttribute with both a DEFAULT value and as NOT NULL.

Code

database.execSQL("ALTER TABLE tableName ADD COLUMN newAttribute INTEGER DEFAULT 0 NOT NULL")

Full Code

@Database(entities = arrayOf(ModelName::class), version = 2)
@TypeConverters(Converters::class)
abstract class DatabaseName : RoomDatabase() {

    abstract fun daoName(): DaoName

    companion object {

        private var INSTANCE: DatabaseName? = null

        fun getAppDatabase(context: Context): DatabaseName {
            if (INSTANCE == null) {
                INSTANCE = Room.databaseBuilder(context.applicationContext,
                        DatabaseName::class.java, DATABASE_NAME)
                        .addMigrations(MIGRATION_1_2)
                        .build()
            }
            return INSTANCE as DatabaseName
        }

        val MIGRATION_1_2: Migration = object : Migration(1, 2) {
            override fun migrate(database: SupportSQLiteDatabase) {
                database.execSQL("ALTER TABLE tableName ADD COLUMN newAttribute INTEGER DEFAULT 0 NOT NULL")
            }
        }
    }

}