How to implement async | await to receive distance with geoLocation package? - flutter

Question

I am implementing a ListView that will show a Card with the distance between the user and each card location, the location of the card is obtained from Firestore. Im using the geoLocator package but i have an issue to receive the distance, i got null when i call the method and i know that i have to use async-wait in order to wait for the value of the distance but i do not know where to implement it.
This is the class that i call to the get the distance:
class Distance {
double distance;
void getDistance(double startLatitude, double startLongitude, double endLatitude,
double endLongitude) async {
try {
distance = await Geolocator().distanceBetween(
startLatitude, startLongitude, endLatitude, endLongitude);
} catch (e) {
print('SE DISPARO EL ERROR DE DISTANCE = $e');
}
}
This is the Widget that i return:
Widget cardList(double userLatitude, double userLongitude) {
double result;
// Method to get the distance
dynamic getDistance(double cardLatitude, double cardLongitude) async {
Distance distancia = Distance();
await distancia.getDistance(
userLatitude, userLongitude, cardLatitude, cardLongitude);
result = distancia.distance;
return result;
}
return StreamBuilder<QuerySnapshot>(
stream: _firestore.collection('salonesInfantiles').snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.pink,
),
);
}
final rooms = snapshot.data.documents.reversed;
List<SalonesFeed> listaDeSalones = [];
// List<SalonesFeed> listaDeSalonesDistancia = [];
for (var room in rooms) {
final nombreSalonText = room.data['nombre'];
final salonLatitude = room.data['latitude'];
final salonLongitude = room.data['longitude'];
// This is the method that i dont know how to implement the wait in order to receive the value before the ListView is showed
double distance = getDistance(salonLatitude, salonLongitude);
print('result 2 = $result');
final salonCard = SalonesFeed(
nombreSalon: nombreSalonText,
distanciaSalon: distance,
);
listaDeSalones.add(salonCard);
}
return Expanded(
child: ListView(
children: listaDeSalones,
),
);
},
);
}
I got this result:
type 'Future<dynamic>' is not a subtype of type 'double'
I also try to make it Future but still have the same issue of null
type 'Future<double>' is not a subtype of type 'double'

Answer 1

The return type of getDistance should be Future and you should await the response
double distance = await getDistance(salonLatitude, salonLongitude);