snapshot.hasdata返回false，即使响应也有数据[flutter]

Question

我正在尝试从OpenWeather获取当前的天气信息，并在检查返回数据后在文本小部件中显示结果。但是，始终将Condtion（Snapshot.hasdata）返回为false，否则调用条件（循环刺激器）。 这是FutureBuilder。

class WeatherPage extends StatefulWidget {
  @override
  State<WeatherPage> createState() => _WeatherPageState();
}

class _WeatherPageState extends State<WeatherPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: FutureBuilder(
          future: getCurrentWeather(),
          builder: (context, snapshot) {
            if (snapshot.hasData) {
              WeatherModelCurrent weather =
                  snapshot.data as WeatherModelCurrent;

              return weatherBox(weather);
            } else {
              return const CircularProgressIndicator();
            }
          },
        ),
      ),
    );
  }

这是getCurrentWeather（）函数

Future getCurrentWeather() async {
    WeatherModelCurrent? weather;

    var url = Uri.parse(
        "https://api.openweathermap.org/data/2.5/weather?q=Kathmandu&appid=82c7b99e2a8215351147f607592a3e63&units=metric");
    var response = await http.get(url);
//response.body has the data returned by API call
    print(response.body);

    if (response.statusCode == 200) {
      weather = WeatherModelCurrent.frommJson(jsonDecode(response.body));
    
    } else {
      print('error');
    }

    return weather;
  }

，这是模型类

class WeatherModelCurrent {
  double temp;
  double feelslike;
  double tempmin;
  double tempmax;
  String description;

  WeatherModelCurrent(
      {required this.temp,
      required this.feelslike,
      required this.tempmin,
      required this.tempmax,
      required this.description});

  factory WeatherModelCurrent.frommJson(Map<String, dynamic> jsonn) {
    return WeatherModelCurrent(
      temp: jsonn['main']['temp'].toDouble(),
      feelslike: jsonn['main']['feels_like'].toDouble(),
      tempmin: jsonn['main']['temp_min'].toDouble(),
      tempmax: jsonn['main']['temp_max'].toDouble(),
      description: jsonn['weather']['description'],
    );
  }
}

Answer 1

尝试＆amp;捕获您的getCurrentWeather代码块，我们可以获得以下例外：

flutter: exception type 'String' is not a subtype of type 'int' of 'index'

响应json类似：

{
    "weather":[
        {
            "id":803,
            "main":"Clouds",
            "description":"broken clouds",
            "icon":"04d"
        }
    ],
}

您的代码description：jsonn ['ateathy'] ['description'] ['description']应该是描述：JSONN ['天气'] [0] ['Description']，

Answer 2

发生错误是因为您将响应解析为错误的班级。
尝试此模型类

 class WeatherModelCurrent {
  WeatherModelCurrent({
this.coord,
this.weather,
this.base,
this.main,
this.visibility,
this.wind,
this.clouds,
this.dt,
this.sys,
this.timezone,
this.id,
this.name,
this.cod,
 });

 final Coord? coord;
 final List<Weather>? weather;
 final String? base;
final Main? main;
 final int? visibility;
 final Wind? wind;
 final Clouds? clouds;
 final int? dt;
 final Sys? sys;
 final int? timezone;
 final int? id;
 final String? name;
   final int? cod;

     factory WeatherModelCurrent.fromJson(Map<String, dynamic> json) =>  WeatherModelCurrent(
coord: Coord.fromJson(json["coord"]),
weather: List<Weather>.from(json["weather"].map((x) =>   Weather.fromJson(x))),
base: json["base"],
main: Main.fromJson(json["main"]),
visibility: json["visibility"],
wind: Wind.fromJson(json["wind"]),
clouds: Clouds.fromJson(json["clouds"]),
dt: json["dt"],
sys: Sys.fromJson(json["sys"]),
timezone: json["timezone"],
id: json["id"],
name: json["name"],
cod: json["cod"],
  );

  Map<String, dynamic> toJson() => {
  "coord": coord!.toJson(),
"weather": List<dynamic>.from(weather!.map((x) => x.toJson())),
"base": base,
"main": main!.toJson(),
"visibility": visibility,
"wind": wind!.toJson(),
"clouds": clouds!.toJson(),
"dt": dt,
"sys": sys!.toJson(),
"timezone": timezone,
"id": id,
"name": name,
"cod": cod,
};
}

class Clouds {
 Clouds({
this.all,
});

final int? all;

 factory Clouds.fromJson(Map<String, dynamic> json) => Clouds(
all: json["all"],
 );

 Map<String, dynamic> toJson() => {
 "all": all,
  };
 }

  class Coord {
 Coord({
this.lon,
this.lat,
});

final double? lon;
 final double? lat;

 factory Coord.fromJson(Map<String, dynamic> json) => Coord(
  lon: json["lon"].toDouble(),
  lat: json["lat"].toDouble(),
);

Map<String, dynamic> toJson() => {
"lon": lon,
"lat": lat,
 };
  }

  class Main {
Main({
this.temp,
this.feelsLike,
this.tempMin,
this.tempMax,
this.pressure,
this.humidity,
 });

 final double? temp;
final double? feelsLike;
final double? tempMin;
final double? tempMax;
final int? pressure;
final int? humidity;

factory Main.fromJson(Map<String, dynamic> json) => Main(
temp: json["temp"].toDouble(),
feelsLike: json["feels_like"].toDouble(),
tempMin: json["temp_min"].toDouble(),
tempMax: json["temp_max"].toDouble(),
pressure: json["pressure"],
humidity: json["humidity"],
);

Map<String, dynamic> toJson() => {
"temp": temp,
"feels_like": feelsLike,
"temp_min": tempMin,
"temp_max": tempMax,
"pressure": pressure,
"humidity": humidity,
  };
    }

 class Sys {
 Sys({
this.type,
this.id,
this.country,
this.sunrise,
this.sunset,
 });

 final int? type;
 final int? id;
final String? country;
final int? sunrise;
 final int? sunset;

 factory Sys.fromJson(Map<String, dynamic> json) => Sys(
type: json["type"],
id: json["id"],
country: json["country"],
sunrise: json["sunrise"],
sunset: json["sunset"],
 );

 Map<String, dynamic> toJson() => {
"type": type,
"id": id,
"country": country,
"sunrise": sunrise,
"sunset": sunset,
 };
  }

  class Weather {
  Weather({
this.id,
this.main,
this.description,
this.icon,
});

final int? id;
final String? main;
final String? description;
final String? icon;

 factory Weather.fromJson(Map<String, dynamic> json) => Weather(
  id: json["id"],
  main: json["main"],
  description: json["description"],
  icon: json["icon"],
);

Map<String, dynamic> toJson() => {
"id": id,
"main": main,
"description": description,
"icon": icon,
 };
}

  class Wind {
  Wind({
this.speed,
this.deg,
});

final double? speed;
final int? deg;

 factory Wind.fromJson(Map<String, dynamic> json) => Wind(
  speed: json["speed"].toDouble(),
  deg: json["deg"],
   );

Map<String, dynamic> toJson() => {
  "speed": speed,
  "deg": deg,
};
  }