Store with Room

RoomStore.kt

@Entity
data class User(
        @PrimaryKey(autoGenerate = true) var uid: Int = 0,
        val name: String,
        val lastName: String)


@Dao
interface UserDao {
    @Query("SELECT name FROM user")
    fun loadAll(): Flowable<List<String>>
    

    @Insert
    fun insertAll(vararg users: User)

    @Delete
    fun delete(user: User)
}

@Database(entities = arrayOf(User::class), version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

val db = Room.databaseBuilder(SampleApp.appContext, AppDatabase::class.java, "db").build()



//store
class SampleRoomStore(fetcher: Fetcher<User, String>,
                      persister: RoomPersister<User, List<String>, String>,
                      stalePolicy: StalePolicy = StalePolicy.UNSPECIFIED) :
        RoomInternalStore<User, List<String>, String>(fetcher, persister, stalePolicy)

val persister = object : RoomPersister<User, List<String>, String> {
    override fun read(key: String): Observable<List<String>> {
        return db.userDao().loadAll().toObservable().map { if (it.isEmpty()) throw Exception() else it }
    }

    override fun write(key: String, user: User) {
        db.userDao().insertAll(user)
    }

}


val fetcher=Fetcher<User,String> { Single.just(User(name = "Mike", lastName = "naki")) }

val store = SampleRoomStore( fetcher, persister)


//Usage
   var foo = store.get("")
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe({ strings1 -> val success = strings1 != null }) { throwable -> throwable.stackTrace }

        foo = Observable.timer(15, TimeUnit.SECONDS)
                .subscribe { it -> again() }
    }

    private fun again() {
        val bar = store.fetch("")
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe({ strings1 -> val success = strings1 != null }) { throwable -> throwable.stackTrace }
    }