I am deveoping an app in Flutter using GetX state management, but having a difficult time getting address from GPS on the spot. I am using Geocoder and geolocator to fetch latitude, longitude, and address based on coordinates. I have a Floatingactionbutton that scans a barcode and adds some data to Firestore: latitude, longitude, and address.
The problem I am having is I am seeing data like this adding to Firestore(below). Sometimes I have to scan like 3 times before the address and coordinates are added to firestore. How do I make sure the coordinates and address are fetched first before adding to firestore. Using a stateful widget I believe I could do it in the initstate?
'''
class ScanController extends GetxController {
final userName = "".obs;
String name = "";
String latitude, longitude;
String address = "";
String timeFormat = "";
String result = "Hey there !";
List scannedLocation = [];
Future<String> futureAddress;
Future<String> getUserDisplayName() async {
final snapshot =
await _firestore.collection('users').doc(_auth.currentUser.uid).get();
name = snapshot.data()['displayName'];
return name;
}
setName() async {
String returnString = await getUserDisplayName();
userName(returnString);
update();
}
setSnackBar(title, message) {
Get.snackbar(title, message,
duration: Duration(seconds: 3),
backgroundColor: Colors.black,
colorText: Colors.white,
snackPosition: SnackPosition.BOTTOM);
update();
}
getCurrentLocation() async {
try {
final position = await Geolocator()
.getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
latitude = '${position.latitude}';
longitude = '${position.longitude}';
} catch (e) {
setSnackBar("Hello", "getCurrentLocation() Error: $e");
}
}
Future<String> getAddressBasedOnLocation() async {
try {
final coordinates =
new Coordinates(double.parse(latitude), double.parse(longitude));
var addresses =
await Geocoder.local.findAddressesFromCoordinates(coordinates);
address = addresses.first.addressLine;
} catch (e) {
setSnackBar("Hello", "getAddressBasedOnLocation Error: $e");
}
return address;
}
Future scanQR() async {
try {
// QR data
String qrResult = await BarcodeScanner.scan();
// String location to be outputted onto screen
String locationOneTime;
// Current date and time
final now = DateTime.now();
timeFormat = DateFormat('hh:mm a').format(now);
// get latitude and longitude coordinates
getCurrentLocation();
// get address based on latitude and longitude
futureAddress = getAddressBasedOnLocation();
address.toString();
locationOneTime = '$qrResult scanned at $timeFormat in $address';
print(locationOneTime);
scannedLocation.add(locationOneTime);
setSnackBar("Notification", "Scan Successful");
result = qrResult;
_firestore.collection('messages').add({
'user': _auth.currentUser.email,
'location': result,
'timestamp': FieldValue.serverTimestamp(),
'coordinates': '$latitude: $longitude',
'address': '$address',
});
} on PlatformException catch (ex) {
if (ex.code == BarcodeScanner.CameraAccessDenied) {
setSnackBar("Hello", "Camera permission was denied");
} else {
setSnackBar("Hello", "Unknown error $ex");
}
} on FormatException {
setSnackBar(
"Hello", "You pressed the back button before scanning anything");
} catch (ex) {
setSnackBar("Hello", "Unknown Error $ex");
}
}
}
'''
It is because you are not waiting for the future to complete. You should use the await
operator
Future scanQR() async {
try {
// QR data
String qrResult = await BarcodeScanner.scan();
// String location to be outputted onto screen
String locationOneTime;
// Current date and time
final now = DateTime.now();
timeFormat = DateFormat('hh:mm a').format(now);
// get latitude and longitude coordinates
// add await here
await getCurrentLocation();
// get address based on latitude and longitude
//// add await here
futureAddress = await getAddressBasedOnLocation();
address.toString();
locationOneTime = '$qrResult scanned at $timeFormat in $address';
print(locationOneTime);
scannedLocation.add(locationOneTime);
setSnackBar("Notification", "Scan Successful");
result = qrResult;
_firestore.collection('messages').add({
'user': _auth.currentUser.email,
'location': result,
'timestamp': FieldValue.serverTimestamp(),
'coordinates': '$latitude: $longitude',
'address': '$address',
});
} on PlatformException catch (ex) {
if (ex.code == BarcodeScanner.CameraAccessDenied) {
setSnackBar("Hello", "Camera permission was denied");
} else {
setSnackBar("Hello", "Unknown error $ex");
}
} on FormatException {
setSnackBar(
"Hello", "You pressed the back button before scanning anything");
} catch (ex) {
setSnackBar("Hello", "Unknown Error $ex");
}
}
}