Reputation: 710
I want to pre-populate my Room database from the json file in the assets folder. I follow the Google Sunflower sample. I copied the SeedDatabaseWorker class:
import android.content.Context
import android.util.Log
import androidx.work.Worker
import androidx.work.WorkerParameters
import com.dmitrysimakov.gymlab.data.GymLabDb
import com.dmitrysimakov.gymlab.data.entity.Training
import com.google.gson.Gson
import com.google.gson.reflect.TypeToken
import com.google.gson.stream.JsonReader
import javax.inject.Inject
class SeedDatabaseWorker(val context: Context, workerParams: WorkerParameters) : Worker(context, workerParams) {
private val TAG = SeedDatabaseWorker::class.java.simpleName
@Inject lateinit var database: GymLabDb
override fun doWork(): Worker.Result {
val plantType = object : TypeToken<List<Training>>() {}.type
var jsonReader: JsonReader? = null
return try {
val inputStream = context.assets.open("training.json")
jsonReader = JsonReader(inputStream.reader())
val plantList: List<Training> = Gson().fromJson(jsonReader, plantType)
database.trainingDao().insert(plantList)
Worker.Result.SUCCESS
} catch (ex: Exception) {
Log.e(TAG, "Error seeding database", ex)
Worker.Result.FAILURE
} finally {
jsonReader?.close()
}
}
}
I'm using Dagger 2, so instead of doing this: Sunflower AppDatabase, I do this:
import android.arch.persistence.db.SupportSQLiteDatabase
import android.arch.persistence.room.Room
import android.arch.persistence.room.RoomDatabase
import androidx.work.OneTimeWorkRequestBuilder
import androidx.work.WorkManager
import com.dmitrysimakov.gymlab.GymLabApp
import com.dmitrysimakov.gymlab.data.GymLabDb
import com.dmitrysimakov.gymlab.workers.SeedDatabaseWorker
import dagger.Module
import dagger.Provides
import javax.inject.Singleton
@Module(includes = [ViewModelModule::class])
class AppModule {
@Singleton
@Provides
fun provideDb(app: GymLabApp): GymLabDb {
return Room
.databaseBuilder(app, GymLabDb::class.java, "gymlab.db")
.addCallback(object : RoomDatabase.Callback() {
override fun onCreate(db: SupportSQLiteDatabase) {
super.onCreate(db)
val request = OneTimeWorkRequestBuilder<SeedDatabaseWorker>().build()
WorkManager.getInstance().enqueue(request)
}
})
.fallbackToDestructiveMigration()
.build()
}
@Singleton
@Provides
fun provideTrainingDao(db: GymLabDb) = db.trainingDao()
}
But I can't inject the database that has not yet been created. So, how can I access the dao?
Upvotes: 5
Views: 3913
Reputation: 710
The problem was that I couldn't inject my database into the Worker. I found the solution here: AndroidWorkerInjection
Upvotes: 2
Reputation: 12118
Your issue is that SeedDatabaseWorker
is still based on Worker()
which is deprecated now, so you need to use Worker(Context, WorkerParameters)
this constructor.
Check my answer from another post, it'll help you understand WorkManager
library.
You can now check Worker from that Sunflower demo, it's updated.
Upvotes: 1