从异步函数返回 List<LatLng> 但接收函数仍然认为它是 Future<List<LatLng>>

Question

我正在尝试将 Future<List> 转换为 List 以便我可以在 for 循环中使用它在谷歌地图上创建标记。但是，当我在一个函数中使用 await 转换它并将其返回给另一个函数时，第二个函数仍然认为它是 Future<List>。

这是我的代码：

class mapPage extends StatelessWidget {
  late GoogleMapController mapController;

  final LatLng _center = const LatLng(51.49759646223456, -0.22884194229223435);
  // function that converts
  Future<List<LatLng>> getLocations(context) async {
    List<LatLng> locations = await buildLocations(context);
    return locations;
  }

  Set<Marker> _createMarker(context) {
    // attempt to retrieve result of converting function (where error occurs)
    List<LatLng> locations = getLocations(context);

    return {
      Marker(
          markerId: const MarkerId("marker_1"),
          position: _center,
          infoWindow: const InfoWindow(
            title: "",
            snippet: "",
          ),
          onTap: () => Navigator.push(
                context,
                MaterialPageRoute(builder: (context) => listPage2()),
              )),
      Marker(markerId: MarkerId(stores[0]), position: locations[0]),
      const Marker(
        markerId: MarkerId("marker_2"),
        position: LatLng(51.488348, -0.237461),
        icon: BitmapDescriptor.defaultMarker,
      ),
    };
  }

  void _onMapCreated(GoogleMapController controller) {
    mapController = controller;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GoogleMap(
          onMapCreated: _onMapCreated,
          initialCameraPosition: CameraPosition(
            target: _center,
            zoom: 11.0,
          ),
          markers: _createMarker(context)),
    );
  }

  @override
  Future<List<LatLng>> buildLocations(BuildContext context) async {
    List<LatLng> locations = [];
    var collection = FirebaseFirestore.instance.collection('StoreDatabase');
    var querySnapshot = await collection.get();
    for (var queryDocumentSnapshot in querySnapshot.docs) {
      Map<String, dynamic> document = queryDocumentSnapshot.data();
      LatLng location = document['Location'];
      locations.add(location);
    }
    return locations;
  }

  Future<List<String>> buildStores(BuildContext context) async {
    List<String> stores = [];
    var collection = FirebaseFirestore.instance.collection('StoreDatabase');
    var querySnapshot = await collection.get();
    for (var queryDocumentSnapshot in querySnapshot.docs) {
      Map<String, dynamic> document = queryDocumentSnapshot.data();
      String store = document['storeName'];
      stores.add(store);
    }
    return stores;
  }
}

任何帮助深表感谢！

Answer 1

您需要等待完成未来（获取数据）

 Set<Marker> _createMarker(context) async {
    List<LatLng> locations = await getLocations(context);