Question

每当我尝试获取数据时，都会引发异常：

Exception has occurred.
NoSuchMethodError (NoSuchMethodError: The method 'map' was called on null.
Receiver: null
Tried calling: map<Location>(Closure: (dynamic) => Location))

print(responses)在控制台上打印null。

这是我从api获取响应的功能：

String url1 = 'http://192.168.43.171:3000/location';
Future<void> showLocation() async {
  var response = await http.get(Uri.encodeFull(url1));
  if (response.statusCode == 200) {
    print(response.body);
    // Map<String, dynamic> parsedMap=jsonDecode(response.body);
    final data = json.decode(response.body);
    final responses = Details.fromJson(data[0]);
    print(responses);
    // print(parsedMap['location']);
  } else {
    throw Exception('failed to load');
  }
}

这是我的locationModel.dart：

class Location {
  final String latitude;
  final String longitude;
  Location({this.latitude, this.longitude});
  factory Location.fromJson(Map<String, dynamic> parsedJson) {
    return Location(
        latitude: parsedJson['latitude'], longitude: parsedJson['longitude']);
  }
}

class Details {
  final String username;
  final List<Location> locations;
  Details({this.username, this.locations});
  factory Details.fromJson(Map<String, dynamic> parsedJson) {
    var list = parsedJson['locations'] as List;
    print(list.runtimeType);
    List<Location> locationList =
        list.map((i) => Location.fromJson(i)).toList();

    return Details(username: parsedJson['username'], locations: locationList);
  }
}

我的JSON：

[
  {
    "id":"ABC",
    "username":"xyz",
    "location":[
                {
                     "latitude": "34",
                     "longitude": "343"
                },
                {
                      "latitude": "34",
                      "longitude": "32"
                  }
             ]
  }

{
    "id":"ABC1",
    "username":"xyz1",
    "location":[
                {
                     "latitude": "34222",
                     "longitude": "32243"
                },

             ]
  }

]

Answer 1

您有错字：

    var list = parsedJson['locations'] as List;

vs

location:[

位置！=位置

我正在尝试序列化从api接收到的json，但是没有这样做

1 个答案: