跨异步间隙的 BuildContexts 问题答案

【问题标题】：Problem with BuildContexts across sync gaps跨异步间隙的 BuildContexts 问题
【发布时间】：2022-12-31 02:14:35
【问题描述】：

我正在尝试通过学习 Angela Yu 课程来学习 Flutter，这似乎有点过时了，我正面临这个问题：“不要在异步间隙中使用 BuildContexts”，在以下代码中；

void getLocationData() async {
    Location location = Location();

    await location.getCurrentLocation();

    NetworkHelper networkHelper = NetworkHelper(
        'https://api.openweathermap.org/data/2.5/weather?lat=${location.latitude}&lon=${location.longitude}&appid=$apiKey&units=metric');

    var weatherData = await networkHelper.getData();

    Navigator.push(context, MaterialPageRoute(builder: (context) {
      return LocationScreen(locationWeather: weatherData);
    }));
  }

我试图在网上查看解决方案，但似乎找不到我的查询的答案。任何反馈将不胜感激。

附言我尝试使用：

if (mounted) {
      Navigator.push(context, MaterialPageRoute(builder: (context) {
        return LocationScreen(locationWeather: weatherData);
      }));
    }

但它似乎也不起作用。

【问题讨论】：

标签： flutter dart

【解决方案1】：

您可以尝试使用 WidgetsBinding.instance.addPostFrameCallback 方法来安排在构建完成后进行导航：

void getLocationData() async {
    Location location = Location();

    await location.getCurrentLocation();

    NetworkHelper networkHelper = NetworkHelper(
        'https://api.openweathermap.org/data/2.5/weather?lat=${location.latitude}&lon=${location.longitude}&appid=$apiKey&units=metric');

    var weatherData = await networkHelper.getData();

    // Schedule the navigation to occur after the build is complete
    WidgetsBinding.instance.addPostFrameCallback((_) {
      Navigator.push(context, MaterialPageRoute(builder: (context) {
        return LocationScreen(locationWeather: weatherData);
      }));
    });
  }

或者您可以尝试在 await networkHelper.getData() 块内移动 Navigator.push 调用，如下所示：

void getLocationData() async {
    Location location = Location();

    await location.getCurrentLocation();

    NetworkHelper networkHelper = NetworkHelper(
        'https://api.openweathermap.org/data/2.5/weather?lat=${location.latitude}&lon=${location.longitude}&appid=$apiKey&units=metric');

    var weatherData = await networkHelper.getData();

    // Navigate to the LocationScreen after the async call is complete
    Navigator.push(context, MaterialPageRoute(builder: (context) {
      return LocationScreen(locationWeather: weatherData);
    }));
  }

【讨论】：