'Future<Stations>' 类型不是 'Iterable<dynamic>' 类型的子类型

Question

API 调用由按钮按下触发，此按钮调用 AnchoredMapMarkers 应在预加载的地图上显示纬度/经度图钉

在async 之后返回print('step5.1_APICALL'); 好

错误显示为type 'Future<Stations>' is not a subtype of type 'Iterable<dynamic>'

非常感谢任何帮助

API 调用并以列表形式正常显示 - 我现在尝试从 Json 中提取纬度/经度并将其绘制在我的地图 SDK 上

class MapMarkerExample{
  
    
 void showAnchoredMapMarkers() { 
  var stations;
       stations = fetchStations(); 
       for (Station stations in stations) {
           GeoCoordinates geoCoordinates = GeoCoordinates (stations.place.location.lat, stations.place.location.lng);
       
           _addCircleMapMarker(geoCoordinates, 0);
           _addPOIMapMarker(geoCoordinates, 1);
           
           } 
        }


  Future<Stations> fetchStations() async {
  print('step5.1_APICALL');
    var client = http.Client();

      final response = await client.get(
      'https://transit.hereapi.com/v8/stations?in=lat,-long&return=transport&apiKey=API_KEY');
   
    if (response.statusCode == 200) {
    return Stations.fromJson(jsonDecode(response.body)); 
    } else {
    throw Exception('Failed to load stations');
    }
  }

 

Answer 1

你不是在等待你的未来。为了使编译器更加复杂，您以某种方式拆分声明和赋值。并重用了一个变量名。

修复：

Future<void> showAnchoredMapMarkers() async { 
    final stations = await fetchStations();

    for (Station station in stations) {  
    ... 

Answer 2

你需要等待

Future<void> showAnchoredMapMarkers() async {
  var stations = await fetchStations();
  for (Station stations in stations) {
    GeoCoordinates geoCoordinates = GeoCoordinates (stations.place.location.lat, stations.place.location.lng);
    
    _addCircleMapMarker(geoCoordinates, 0);
    _addPOIMapMarker(geoCoordinates, 1);
  } 
}