how to add a points system to an app preferences DataStore Jetpack Compose - kotlin

Question

I'm working on a Quiz app and I'm trying to add a points system to the app so that everytime the user gets a question right he gets a +1pts.
and for storing the points I use jetpack compose preferences Datastore.
the problem is whenever I want to add a point to the already saved points it doesn't work.
this is my PointsData
class PointsData(private val context: Context) {
//create the preference datastore
companion object{
private val Context.datastore : DataStore<Preferences> by preferencesDataStore("points")
val CURRENT_POINTS_KEY = intPreferencesKey("points")
}
//get the current points
val getpoints: Flow<Int> =context.datastore.data.map { preferences->
preferences[CURRENT_POINTS_KEY] ?: 0
}
// to save current points
suspend fun SaveCurrentPoints(numPoints : Int){
context.datastore.edit {preferences ->
preferences[PointsData.CURRENT_POINTS_KEY] = numPoints
}
}
}
save points methode
class SavePoints {
companion object {
#Composable
fun savepoints(numPointsToSave : Int) {
val context = LocalContext.current
val scope = rememberCoroutineScope()
val datastore = PointsData(context)
LaunchedEffect(1) {
scope.launch {
datastore.SaveCurrentPoints(numPointsToSave)
}
}
}
}
}
and whenever i want to get the number of points from my DataStore i use
val pointsdatastore = PointsData(context)
val currentpoints = pointsdatastore.getpoints.collectAsState(initial = 0)
//display it as text for example
Text(text = currentpoints.value.toString(), fontSize = 30.sp, fontWeight = FontWeight.Bold,
color = Color.White)
and to do the operation i want (add +1 o the already existing points i do this
val pointsdatastore = PointsData(context)
val currentpoints = pointsdatastore.getpoints.collectAsState(initial = 0)
SavePoints.savepoints(numPointsToSave = currentpoints.value + 1)
but it doesn't seem to work because the number of points always stays 1.
if you know whats the problem please help.

Answer 1

I found the answer my self but for anyone who is stuck in same situation the solution is to another method in PointsData(look at the question provided code)
the method is:
suspend fun incrementpoints(){
context.datastore.edit { preferences->
val currentpoints = preferences[CURRENT_POINTS_KEY] ?: 0
preferences[CURRENT_POINTS_KEY] = currentpoints + 1
}
}
(if you want decrement not increment you can just change + to - )
and now in the PointsMethod(look at the question provided code) you should add
#Composable
fun incrementpoints() {
val context = LocalContext.current
val scope = rememberCoroutineScope()
val datastore = PointsData(context)
LaunchedEffect(key1 = 1) {
scope.launch {
datastore.incrementpoints()
}
}
}