I get page data from a database, I have a repository that returns a flow.
class RepositoryImpl (private val db: AppDatabase) : Repository {
override fun fetchData (page: Int) = flow {
emit(db.getData(page))
}
}
In the ViewModel, I call the stateIn(), the first page arrives, but then how to request the second page? By calling fetchData(page = 2) I get a new flow, and I need the data to arrive on the old flow.
class ViewModel(private val repository: Repository) : ViewModel() {
val dataFlow = repository.fetchData(page = 1).stateIn(viewModelScope, WhileSubscribed())
}
How to get the second page in dataFlow?
CodePudding user response:
I don't see the reason to use a flow in the repository if you are emitting only one value. I would change it to a suspend
function, and in the ViewModel
I would update a variable of type MutableStateFlow
with the new value. The sample code could look like the following:
class RepositoryImpl (private val db: AppDatabase) : Repository {
override suspend fun fetchData (page: Int): List<Data> {
return db.getData(page)
}
}
class ViewModel(private val repository: Repository) : ViewModel() {
val _dataFlow = MutableStateFlow<List<Data>>(emptyList())
val dataFlow = _dataFlow.asStateFlow()
fun fetchData (page: Int): List<Data> {
viewModelScope.launch {
_dataFlow.value = repository.fetchData(page)
}
}
}