Shows how a RoomDatabase.Callback can be used to add database triggers when a database is created.

AppDatabase.kt

@Database(...)
abstract class AppDatabase : RoomDatabase() {
    abstract fun appDao(): AppDao

    companion object {
        private var INSTANCE: AppDatabase? = null
            private set

        fun getInMemoryDatabase(context: Context): CCDatabase {
            if (INSTANCE == null) {
                INSTANCE = Room.databaseBuilder(context,
                        AppDatabase::class.java, "app_database.db")
                        .addCallback(CALLBACK)
                        .build()
            }

            return INSTANCE!!
        }

        private val CALLBACK = object : RoomDatabase.Callback() {
            override fun onCreate(db: SupportSQLiteDatabase) {
                super.onCreate(db)

                db.execSQL("CREATE TRIGGER ...")
            }
        }
    }
}

Can I use INSTANCE in callback? Because I want to put some initial data which has to be added only once. If yes, is there any possibility to implement such with Dagger Hilt?

if you meant like pre-populating your db, for sure you can do that in here. i am not sure about Dagger Hilt, though.

Thanks a lot! i was looking for that solution :D

private val CALLBACK = object : RoomDatabase.Callback() {
            override fun onCreate(db: SupportSQLiteDatabase) {
                super.onCreate(db)

                db.execSQL("CREATE TRIGGER ...")
            }
        }