This is the first time I trid imlementing Flow with Firebase using the MVVM Architectural Pattern. The issue here is when I press loadbutton Data is loaded in the textview. But then when I upload new data and try and get the new data along with the old it doesn't work, It just displays the old data. After restarting the app it provides with the new data. Below is the code.
Repository
@ExperimentalCoroutinesApi
class PostsRepository {
private val mPostsCollection =
FirebaseFirestore.getInstance().collection(Constants.COLLECTION_POST)
fun getAllPosts() = flow<State<List<Post>>> {
emit(State.loading())
val snapshot = mPostsCollection.get().await()
val posts = snapshot.toObjects((Post::class.java))
emit(State.success(posts))
}.catch {
emit(State.failed(it.message.toString()))
}.flowOn(Dispatchers.IO)
fun addPosts(post: Post) = flow<State<DocumentReference>>
{
emit(State.loading())
val postref = mPostsCollection.add(post).await()
emit(State.success(postref))
}.catch {
emit(State.failed(it.message.toString()))
}.flowOn(Dispatchers.IO)
}
State Class
sealed class State<T> {
class Loading<T> : State<T>()
data class Success<T>(val data: T) : State<T>()
data class Failed<T>(val message: String) : State<T>()
companion object {
fun <T> loading() = Loading<T>()
fun <T> success(data: T) = Success(data)
fun <T> failed(message: String) = Failed<T>(message)
}
}
The ViewModel
@ExperimentalCoroutinesApi
class MainViewModel(private val repository: PostsRepository):ViewModel() {
// fun getAllposts() = repository.getAllPosts()
val getallpostlivedata :LiveData<State<List<Post>>> = repository.getAllPosts().asLiveData()
fun addpost(post: Post) = repository.addPosts(post)
}
The MainActivity
@ExperimentalCoroutinesApi
class MainActivity : AppCompatActivity(), View.OnClickListener {
private lateinit var viewModel: MainViewModel
private lateinit var binding: ActivityMainBinding
private val uiScope = CoroutineScope(Dispatchers.Main)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
viewModel = ViewModelProvider(this, MainViewModelFactory()).get(MainViewModel::class.java)
binding.buttonLoad.setOnClickListener(this)
binding.buttonAdd.setOnClickListener(this)
}
private suspend fun addPost(post: Post) {
viewModel.addpost(post).collect{ state ->
when (state) {
is State.Loading -> {
showToast("Loading")
binding.buttonAdd.isEnabled = false
}
is State.Success -> {
showToast("Posted")
binding.fieldPostContent.setText("")
binding.buttonAdd.isEnabled = true
}
is State.Failed -> {
showToast("Failed! ${state.message}")
binding.buttonAdd.isEnabled = true
}
}
}
}
override fun onClick(v: View?) {
when (v!!.id) {
binding.buttonLoad.id -> {
uiScope.launch {
loadPosts()
}
}
binding.buttonAdd.id -> {
uiScope.launch {
addPost(
Post(
postContent = binding.fieldPostContent.text.toString(),
postAuthor = "Karunesh Palekar"
)
)
}
}
}
}
private fun loadPosts() {
viewModel.getallpostlivedata.observe(this, Observer { state->
when(state){
is State.Loading ->{
showToast("Loading")
}
is State.Success ->{
val postText = state.data.joinToString("\n") {
"${it.postContent} ~ ${it.postAuthor}"
}
binding.textPostContent.text = postText
}
is State.Failed ->{
showToast("Failed! ${state.message}")
}
}
})
}
private fun showToast(message: String) {
Toast.makeText(applicationContext, message, Toast.LENGTH_SHORT).show()
}
}
Thank-You for helping out.
