有没有一种方法可以在 Dart 中使用 Future 值来填充文本字段？

Question

我一直在用 flutter 学习 Dart 并正在创建 Weather App 进行练习，我成功地创建了 UI，我使用了 Dark Sky weather API 因为它有 7 天的天气预报但我没有走解码 json 和模型的漫长道路，而是使用了 Dark Sky Library。这是 API

的代码

Future<Null> getWeather() async {
Location location = Location();
await location.getCurrentPosition();
var darksky = DarkSkyWeather(
  MY_API_KEY,
  units: Units.SI,
  language: Language.English,
);
var forecast = await darksky.getForecast(
    location.latitude, location.longitude, excludes: [
    Exclude.Hourly,
    Exclude.Minutely,
    Exclude.Alerts,
    Exclude.Flags
    ]);
print(forecast.currently.temperature.round());
print(forecast.daily.data[0].temperatureMax);
 }

我想在函数外部使用预测变量，并在包中的其他数据中填充湿度温度等文本字段。我怎样才能访问它？任何帮助将不胜感激。谢谢

Answer 1

看看这段代码

class _MyHomePageState extends State<MyHomePage> {

  String _data; // This holds the data to be shown

  @override
  void initState() {
    _data = "Press the button"; // This is the initial data // Set it in initState because you are using a stateful widget
    super.initState();
  }

  // Call this to set the new data
  void setData() {
    setState(() { // Remember to use setState() else the changes won't appear
      _data = 'Hello World';
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Message',
            ),
            Text(
              '$_data', // See how the data is fed into this text widget
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: setData, // When I press the button, the new data is set
        child: Icon(Icons.send),
      ), 
    );
  }
}

输出：

最初：

按下按钮后：

在你的代码中做同样的事情。

// Your code modified a bit
// Make sure this is a stateful widget because you are changing values
double _tempNow; // Declare two vars inside the class
double _tempMax;

// Your initState
@override
void initState() {
    _tempNow = 0; // Initial values
    _tempMax = 0;
    super.initState();
}

// Build method
@override
Widget build(BuildContext context) {
    // Your layout Code.....
         Text(
              'Current: $_tempNow' // Here you set the tempNow
         ),
         ......
         Text(
              'Maximum: $_tempMax' // and tempMax in the text widgets
         ),
    // End
}

Future<Null> getWeather() async {
    Location location = Location();
    await location.getCurrentPosition();
    var darksky = DarkSkyWeather(
        "8810b3633934b8c1975c51a2311dc1d0",
        units: Units.SI,
        language: Language.English,
    );
    var forecast = await darksky.getForecast(
        location.latitude, location.longitude, excludes: [
        Exclude.Hourly,
        Exclude.Minutely,
        Exclude.Alerts,
        Exclude.Flags
    ]);

    // Change the values here.
    // After the data is fetched, The changes will be made automatically
    setState(() {
        _tempNow = forecast.currently.temperature.round();
        _tempMax = forecast.daily.data[0].temperatureMax;
    });
 }

以非常相似的方式，您也可以使用文本字段。在这种情况下，您将需要使用 TextEditingController 并在那里设置文本，但在您的情况下，您似乎需要只读文本来向用户显示信息，因此一个简单的文本小部件就足够了

有没有一种方法可以在 Dart 中使用 Future 值来填充文本字段？

Is there a way I can use Future values in Dart to fill Textfields?

futuretask

async-await

dart

flutter