I wanted to build an application like Twitter where I have to display a list of data sets with live updates for counting like and comments in real time.
For that, I am using
- RecyclerView - for displaying list of scrollable data
- Jetpack LiveData - for observing changes and notifying observers.
- Firestore - As a backend for getting realtime data with snapshot changes.
- Paging 3 - for loading large set of data into list by chuncks.
But how would I implement the firestore query with PaggingSource class by emitting live changes to the list?
class FirebasePagingSource() : PagingSource<QuerySnapshot,ItemModel>() {
override fun getRefreshKey(state: PagingState<QuerySnapshot, ItemModel>): QuerySnapshot? {
// Need guidance for implementation
}
override suspend fun load(params: LoadParams<QuerySnapshot>): LoadResult<QuerySnapshot, ItemModel> {
//Need guidance for implementation
} }
Here ItemModel is a data class
2. ItemListLiveData Class
class FirestoreQueryLiveData(private val query: Query)
: LiveData<List<Item>>(), EventListener<QuerySnapshot> {
private lateinit var registration: ListenerRegistration
override fun onActive() {
super.onActive()
registration = query.addSnapshotListener(this)
}
override fun onInactive() {
super.onInactive()
registration.remove()
}
override fun onEvent(snapshot: QuerySnapshot?, error: FirebaseFirestoreException?) {
snapshot?.let {
val documents= mutableListOf<Item>()
for (document in snapshot.documents) {
document.toObject(Item::class.java)?.let {
documents.add(it)
}
}
postValue(documents)
}
} }
