如何从 Firestore 检索位置并显示在 Google 地图上 flutter

Question

正在学习这两个教程：

Flutter Google Maps Firestore Geolocation

Flutter Retrieve Markers From Firestore

我在我的应用程序中集成了地图功能。定位当前用户位置。

我的问题是我想从 firestore 检索其他用户的位置并将其显示在地图上还有。

（或者在这种情况下不是用户而是餐馆提供）

但它没有显示在地图上，知道我做错了什么吗？

这是我的collectionScreenshot

这是完整的工作代码

class _MapScreenState extends State<MapScreen> {
  StreamSubscription _locationSubscription;
   Location _locationTracker = Location();
   Marker marker;
   Circle circle;
   GoogleMapController _controller;

   String location;
   RxList mapList = <OffersModel>[].obs;
   var isLoading = true.obs;

  final allOfferCollection = FirebaseFirestore.instance.collection('all-offers');

   Map<MarkerId, Marker> markers = <MarkerId, Marker>{
   };

   void initState() {
    getMarkerData();
    super.initState();
   }

   void initOffer(specify, specifyId) async
   {
    var p=specify['location'];
    var markerIdVal = specifyId;
    final MarkerId markerId = MarkerId(markerIdVal);
    final Marker marker = Marker(
      markerId: markerId,
      position: LatLng(p['location'].latitude, p['location'].longitutde),
      infoWindow: InfoWindow(title: specify['name'], snippet: specify['location'])
    );
    setState(() {
      markers[markerId] = marker;
    });
   }

   Future<DocumentReference> getMarkerData() async {
    try {
      allOfferCollection.get().then((snapshot) {
      print(snapshot);
      if(snapshot.docs.isNotEmpty){
        for(int i= 0; i < snapshot.docs.length; i++)
          {
            initOffer(snapshot.docs[i].data, snapshot.docs[i].id);
          }
      }
      snapshot.docs
          .where((element) => element["location"] == location)
          .forEach((element) {
        if (element.exists) {
          mapList.add(OffersModel.fromJson(element.data(), element.id));
        }
      });
    });
  } finally {
  isLoading(false);
  }
  }

  static final CameraPosition initialLocation = CameraPosition(
    target: LatLng(36.723062, 3.087800),
    zoom: 14.4746,
    // zoom: 14,

  );

  Future<Uint8List> getMarker() async {
    ByteData byteData = await DefaultAssetBundle.of(context).load("assets/marker.png");
    return byteData.buffer.asUint8List();
  }

  void updateMarkerAndCircle(LocationData newLocalData, Uint8List imageData) {
    LatLng latlng = LatLng(newLocalData.latitude, newLocalData.longitude);
    this.setState(() {
      marker = Marker(
          markerId: MarkerId("home"),
          position: latlng,
          rotation: newLocalData.heading,
          draggable: false,
          zIndex: 2,
          flat: true,
          anchor: Offset(0.5, 0.5),
          icon: BitmapDescriptor.fromBytes(imageData));

    });
  }

  void getCurrentLocation() async {
    try {

      Uint8List imageData = await getMarker();
      var location = await _locationTracker.getLocation();

      updateMarkerAndCircle(location, imageData);

      if (_locationSubscription != null) {
        _locationSubscription.cancel();
      }

      _locationSubscription = _locationTracker.onLocationChanged.listen((newLocalData) {
        if (_controller != null) {
          _controller.animateCamera(CameraUpdate.newCameraPosition(new CameraPosition(
              bearing: 192.8334901395799,
              target: LatLng(newLocalData.latitude, newLocalData.longitude),
              tilt: 0,
              zoom: 18.00
          )));
          updateMarkerAndCircle(newLocalData, imageData);
        }
      });

    } on PlatformException catch (e) {
      if (e.code == 'PERMISSION_DENIED') {
        debugPrint("Permission Denied");
      }
    }
  }

  @override
  void dispose() {
    if (_locationSubscription != null) {
      _locationSubscription.cancel();
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Scaffold(
        body: GoogleMap(
          mapType: MapType.normal,
          initialCameraPosition: initialLocation,
          markers: Set.of((marker != null) ? [marker] : []),
          // circles: Set.of((circle != null) ? [circle] : []),
          onMapCreated: (GoogleMapController controller) {
            setState(() {
              _controller = controller;
            });
          },
          myLocationEnabled: true,
          compassEnabled: true,

        ),
      ),
    );
    }
  }

编辑：这是我的 logcat 问题

    E/flutter (20815): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: NoSuchMethodError: Closure call with mismatched arguments: function '[]'
E/flutter (20815): Receiver: Closure: () => Map<String, dynamic> from Function 'data':.
E/flutter (20815): Tried calling: []("location")
E/flutter (20815): Found: []() => Map<String, dynamic>
E/flutter (20815): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)
E/flutter (20815): #1      _MapScreenState.initOffer (package:fayda/dev/MapScreen/MapScreen.dart:46:18)
E/flutter (20815): #2      _MapScreenState.getMarkerData.<anonymous closure> (package:fayda/dev/MapScreen/MapScreen.dart:70:13)
E/flutter (20815): #3      _rootRunUnary (dart:async/zone.dart:1362:47)
E/flutter (20815): #4      _CustomZone.runUnary (dart:async/zone.dart:1265:19)
E/flutter (20815): <asynchronous suspension>
E/flutter (20815): 
I/chatty  (20815): uid=10168(com.app.fayda) 1.ui identical 2 lines
E/flutter (20815): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: NoSuchMethodError: Closure call with mismatched arguments: function '[]'
E/flutter (20815): Receiver: Closure: () => Map<String, dynamic> from Function 'data':.
E/flutter (20815): Tried calling: []("location")
E/flutter (20815): Found: []() => Map<String, dynamic>

Answer 1

我添加了地理编码器

 Future<DocumentReference> getMarkerData() async {
LatLng pos;
String id, name, loc;
try {
  allOfferCollection.get().then((snapshot) async {
    if (snapshot.docs.isNotEmpty) {
      for (int i = 0; i < snapshot.docs.length; i++) {
        Map<dynamic, dynamic> map = snapshot.docs[i].data();

        id = map['name'];
        name = map['categoryId'];
        loc = map['location'];
        var addresses = await Geocoder.local.findAddressesFromQuery(loc);
        var first = addresses.first;
        pos = new LatLng(
            first.coordinates.latitude, first.coordinates.longitude);
        initOffer(pos, id, name);
      }
    }
  });
} finally {
  isLoading(false);
}
}

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