DAO Injection problem - RoomDatabase not found with Hilt Android

Question

So I'm trying to use Room on a personnal project. I have implemented my entities, dao and my roomdatabase extended application class :

@Database(
version = 1,
entities = [
    UserDBEntity::class
]
)
abstract class MyDatabase: RoomDatabase() {

    companion object {
        const val DATABASE_NAME = "MyDb"
    }

    abstract fun getUserDao(): UserDao
}

However, I'm also trying to use Hilt DI with it, so, I created a module like that :

@InstallIn(ApplicationComponent::class)
@Module
object PersistenceModule {

    lateinit var database: MyDatabase

    @Provides
    @Singleton
    fun provideDatabase(@ApplicationContext context: Context): MyDatabase{
        database =  Room.databaseBuilder(
            context,
            MyDatabase::class.java,
            MyDatabase.DATABASE_NAME
        )
            .fallbackToDestructiveMigration()
            .build()

        return database
    }

    @Provides
    @Singleton
    fun provideUserDao(db: MyDatabase): UserDao {
        return db.getUserDao()
    }
}

Everything seems good to me. However, when I try to compile, I've got this error message :

class file for androidx.room.RoomDatabase not found

Any idea of what I missed ?

If it can help you, I tried to change my build.gradle from this :

implementation "androidx.room:room-runtime:2.3.0-alpha02"

To this :

api "androidx.room:room-runtime:2.3.0-alpha02"

And with that, it compiles succefully, but I don't think it's a good practice, looking the tutorials I found.

Don't hesitate if you need more details on my code.

Thank you for your answers :)

EDIT :

My build.gradle for Room :

implementation "androidx.room:room-runtime:2.3.0-alpha02"
kapt "androidx.room:room-compiler:2.3.0-alpha02"
implementation "android.arch.persistence.room:runtime:1.1.1"
kapt "android.arch.persistence.room:compiler:1.1.1"

With this also :

apply plugin: 'kotlin-kapt'

EDIT 2 :

I think I found what is the cause of the problem. I called my DAO method in a class like that :

@Singleton
class DBManagerImpl @Inject constructor(
    private val userDao: UserDao
) : DBManager {

    override fun insertUser(userDBEntity: UserDBEntity) {
       userDao.insertUser(userDBEntity)
    }
}

It seems the problem is in the userDao injection cause if I comment the "private val userDao: UserDao" line, I don't have the error anymore. So I think my problem comes from my way to inject the dao object.

Answer 1

I faced that problem because I was adding dependencies of room to the core module so for those who using modular architecture be sure you added dependencies of room to the app module also

Answer 2

Since you did not provide how you created your dao object, I've written my own and provide it in this answer. This should work:

Database Class

@Database(version = 1,entities = [UserDBEntity::class])
abstract class MyDataBase() : RoomDatabase() {
    
   abstract fun myDao(): UserDao

   companion object {
      val DATABASE_NAME = "my_db"
   }
}

DAO

@Dao
inteface UserDao {
   // your functions
   @Query("SELECT * FROM UserDBEntity")
   suspend fun get(): List<User>

   @Insert(onConflict = OnConflictStrategy.REPLACE)
   suspend fun insert(entity: UserDBEntity)
}

Room Module

@InstallIn(ApplicationComponent::class)
@Module
object RoomModule {
   @Singleton
   @Provides
   fun provideMyDB(@ApplicationContext context: Context): MyDataBase {
       return Room.databaseBuilder(context, 
               MyDataBase::class.java,
               MyDataBase.DATABASE_NAME
         ).fallbackToDestructiveMigration().build()
   }
}

@Singleton
@Provides
fun provideMyDao(myDB: MyDataBase): UserDao {
    return myDB.myDao()
}