Excpetion _TypeError (type '_Map<Object?, Object?>' is not a subtype of type 'Map<String, dynamic>' in type cast)

Question

hello I'm getting this exception from the code below this application is running with those packages:-

Location:^5.0.1

google_maps_flutter:^2.3.1

flutter_polyline_points:^1.0.0

location: ^5.0.1

exception (method_channel_location.dart):-

Exception has occurred.

_TypeError (type '_Map<Object?, Object?>' is not a subtype of type 'Map<String, dynamic>' in type cast)

code(the function below is responsible on navigation):-

  getNavigation() async {
    bool _serviceEnabled;
    PermissionStatus _permissionGranted;
    final GoogleMapController? controller = await _controller.future;
    location.changeSettings(accuracy: loc.LocationAccuracy.high);
    _serviceEnabled = await location.serviceEnabled();

    if (!_serviceEnabled) {
      _serviceEnabled = await location.requestService();
      if (!_serviceEnabled) {
        return;
      }
    }

    _permissionGranted = await location.hasPermission();
    if (_permissionGranted == PermissionStatus.denied) {
      _permissionGranted = await location.requestPermission();
      if (_permissionGranted != PermissionStatus.granted) {
        return;
      }
    }
    if (_permissionGranted == loc.PermissionStatus.granted) {
      _currentPosition = await location.getLocation();
      curLocation =
          LatLng(_currentPosition!.latitude!, _currentPosition!.longitude!);
      locationSubscription =
          location.onLocationChanged.listen((LocationData currentLocation) {
        controller?.animateCamera(CameraUpdate.newCameraPosition(CameraPosition(
          target: LatLng(currentLocation.latitude!, currentLocation.longitude!),
          zoom: 16,
        )));
        if (mounted) {
          controller
              ?.showMarkerInfoWindow(MarkerId(sourcePosition!.markerId.value));
          setState(() {
            curLocation =
                LatLng(currentLocation.latitude!, currentLocation.longitude!);
            sourcePosition = Marker(
              markerId: MarkerId(currentLocation.toString()),
              icon: BitmapDescriptor.defaultMarkerWithHue(
                  BitmapDescriptor.hueBlue),
              position:
                  LatLng(currentLocation.latitude!, currentLocation.longitude!),
              infoWindow: InfoWindow(
                  title:
                      '${double.parse((getDistance(LatLng(widget.lat, widget.lang)).toStringAsFixed(2)))} km'),
              onTap: () {
                print('market tapped');
              },
            );
          });
          getDirections(LatLng(widget.lat, widget.lang));
        }
      });
    }
  }

Even though the full code is:-

import 'dart:async';
import 'package:applicationservice/main.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter_polyline_points/flutter_polyline_points.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:location/location.dart';
import 'package:location/location.dart' as loc;
import 'dart:math' show cos, sqrt, asin;
import 'package:url_launcher/url_launcher.dart';

class MainScreen extends StatefulWidget {
  final double lat;
  final double lang;
  // const MainScreen({super.key, required this.lat, required this.lang});
  MainScreen(this.lat, this.lang);

  @override
  State<MainScreen> createState() => _MainScreenState();
}

const String google_api_key = "AIzaSyAnpCS9K.......kabKsMAZzsQ";

class _MainScreenState extends State<MainScreen> {
  final Completer<GoogleMapController> _controller = Completer();
  Map<PolylineId, Polyline> polylines = {};
  PolylinePoints polylinePoints = PolylinePoints();
  Location location = Location();
  Marker? sourcePosition, destinationPosition;
  loc.LocationData? _currentPosition;
  LatLng curLocation = LatLng(32.8945, 13.1807);
  StreamSubscription<loc.LocationData>? locationSubscription;
// تحديث الموقع

  @override
  void initState() {
    super.initState();
    addMarker();
    getNavigation();
  }

  @override
  void dispose() {
    locationSubscription?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: sourcePosition == null
            ? Center(child: CircularProgressIndicator())
            : Stack(
                children: [
                  GoogleMap(
                    zoomControlsEnabled: false,
                    polylines: Set<Polyline>.of(polylines.values),
                    initialCameraPosition: CameraPosition(
                      target: curLocation,
                      zoom: 16,
                    ),
                    markers: {sourcePosition!, destinationPosition!},
                    onTap: (latLng) {
                      print(latLng);
                    },
                    onMapCreated: (GoogleMapController controller) {
                      _controller.complete(controller);
                    },
                  ),
                  Positioned(
                    top: 30,
                    left: 15,
                    child: GestureDetector(
                      onTap: () {
                        Navigator.of(context).pushAndRemoveUntil(
                            MaterialPageRoute(builder: (context) => MyApp()),
                            (route) => false);
                      },
                      child: Icon(Icons.arrow_back),
                    ),
                  ),
                  Positioned(
                    bottom: 10,
                    right: 10,
                    child: Container(
                      width: 50,
                      height: 50,
                      decoration: BoxDecoration(
                          shape: BoxShape.circle, color: Colors.blue),
                      child: Center(
                          child: IconButton(
                        icon: Icon(
                          Icons.navigation_outlined,
                          color: Colors.white,
                        ),
                        onPressed: () async {
                          await launchUrl(Uri.parse(
                              'google.navigation:q=${widget.lat},${widget.lang}&key=AIzaSyAnpCS9K8F......pZNb_kabKsMAZzsQ'));
                        },
                      )),
                    ),
                  )
                ],
              ));
  }

  getNavigation() async {
    bool _serviceEnabled;
    PermissionStatus _permissionGranted;
    final GoogleMapController? controller = await _controller.future;
    location.changeSettings(accuracy: loc.LocationAccuracy.high);
    _serviceEnabled = await location.serviceEnabled();

    if (!_serviceEnabled) {
      _serviceEnabled = await location.requestService();
      if (!_serviceEnabled) {
        return;
      }
    }

    _permissionGranted = await location.hasPermission();
    if (_permissionGranted == PermissionStatus.denied) {
      _permissionGranted = await location.requestPermission();
      if (_permissionGranted != PermissionStatus.granted) {
        return;
      }
    }
    if (_permissionGranted == loc.PermissionStatus.granted) {
      _currentPosition = await location.getLocation();
      curLocation =
          LatLng(_currentPosition!.latitude!, _currentPosition!.longitude!);
      locationSubscription =
          location.onLocationChanged.listen((LocationData currentLocation) {
        controller?.animateCamera(CameraUpdate.newCameraPosition(CameraPosition(
          target: LatLng(currentLocation.latitude!, currentLocation.longitude!),
          zoom: 16,
        )));
        if (mounted) {
          controller
              ?.showMarkerInfoWindow(MarkerId(sourcePosition!.markerId.value));
          setState(() {
            curLocation =
                LatLng(currentLocation.latitude!, currentLocation.longitude!);
            sourcePosition = Marker(
              markerId: MarkerId(currentLocation.toString()),
              icon: BitmapDescriptor.defaultMarkerWithHue(
                  BitmapDescriptor.hueBlue),
              position:
                  LatLng(currentLocation.latitude!, currentLocation.longitude!),
              infoWindow: InfoWindow(
                  title:
                      '${double.parse((getDistance(LatLng(widget.lat, widget.lang)).toStringAsFixed(2)))} km'),
              onTap: () {
                print('market tapped');
              },
            );
          });
          getDirections(LatLng(widget.lat, widget.lang));
        }
      });
    }
  }

  getDirections(LatLng dst) async {
    List<LatLng> polylineCoordinates = [];
    List<dynamic> points = [];
    PolylineResult result = await polylinePoints.getRouteBetweenCoordinates(
        google_api_key,
        PointLatLng(curLocation.latitude, curLocation.longitude),
        PointLatLng(dst.latitude, dst.longitude),
        travelMode: TravelMode.driving);
    if (result.points.isNotEmpty) {
      result.points.forEach((PointLatLng point) {
        polylineCoordinates.add(LatLng(point.latitude, point.longitude));
        points.add({'lat': point.latitude, 'lng': point.longitude});
      });
    } else {
      print(result.errorMessage);
    }
    addPolyLine(polylineCoordinates);
  }

  addPolyLine(List<LatLng> polylineCoordinates) {
    PolylineId id = PolylineId('poly');
    Polyline polyline = Polyline(
      polylineId: id,
      color: Colors.blue,
      points: polylineCoordinates,
      width: 5,
    );
    polylines[id] = polyline;
    setState(() {});
  }

  double calculateDistance(lat1, lon1, lat2, lon2) {
    var p = 0.017453292519943295;
    var c = cos;
    var a = 0.5 -
        c((lat2 - lat1) * p) / 2 +
        c(lat1 * p) * c(lat2 * p) * (1 - c((lon2 - lon1) * p)) / 2;
    return 12742 * asin(sqrt(a));
  }

  double getDistance(LatLng destposition) {
    return calculateDistance(curLocation.latitude, curLocation.longitude,
        destposition.latitude, destposition.longitude);
  }

  addMarker() {
    setState(() {
      sourcePosition = Marker(
        markerId: MarkerId('source'),
        position: curLocation,
        icon: BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueAzure),
      );
      destinationPosition = Marker(
        markerId: MarkerId('destination'),
        position: LatLng(widget.lat, widget.lang),
        icon: BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueCyan),
      );
    });
  }
}

your help is very appreciated, thanks.

Answer 1

Replace

polylines[id] = polyline;

with

polylines.update(id, (value) => polyline, ifAbsent: () => polyline);