如何解决怎样才能尽快拿到地址?
我正在使用 GetX 状态管理在 Flutter 中开发一个应用程序,但很难当场从 GPS 获取地址。我正在使用地理编码器和地理定位器根据坐标获取纬度、经度和地址。我有一个 Floatingactionbutton 可以扫描条形码并将一些数据添加到 Firestore:纬度、经度和地址。
我遇到的问题是我看到这样的数据添加到 Firestore(如下)。有时我必须扫描 3 次才能将地址和坐标添加到 firestore。在添加到 firestore 之前,如何确保首先获取坐标和地址。使用有状态小部件,我相信我可以在 initstate 中做到吗?
'''
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 $ex");
}
}
}
'''
解决方法
那是因为你不是在等待未来完成。您应该使用 await
运算符
Future scanQR() async {
try {
// QR data
String qrResult = await BarcodeScanner.scan();
// String location to be outputted onto screen
String locationOneTime;
// Current date and time
final now = DateTime.now();
timeFormat = DateFormat('hh:mm a').format(now);
// get latitude and longitude coordinates
// add await here
await getCurrentLocation();
// get address based on latitude and longitude
//// add await here
futureAddress = await getAddressBasedOnLocation();
address.toString();
locationOneTime = '$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");
}
}
}