使用FutureBuilder时如何仅获取一次数据? [英] How to fetch data only once when using FutureBuilder?

问题描述

我有一个获取请求，并将其作为将来传递给FutureBuilder-

I have a fetch request and I am passing it as a future to FutureBuilder -

FutureBuilder(
    future: gettask(),
    builder: (context, snapshot){
        if(snapshot.hasData){

//           Stopwatch stopwatchbefore = new Stopwatch()..start();
//           print('futurebuilder executed in ${stopwatchbefore.elapsed}');

             return SingleChildScrollView(child: listViewWidget(snapshot.data));

        }else{
             return  Center(child: CircularProgressIndicator());
        }
    },
)

然而，方法gettask()似乎在重复获取事件.我尝试使用 https://pub.dev/packages/memoize 和

The method gettask() however, seems to be fetching events repeatedly. I tried to use https://pub.dev/packages/memoize and https://api.flutter.dev/flutter/package-async_async/AsyncMemoizer-class.html but i think they are deprecated since it says that AsyncMemoizer is undefined (no import option available).

我也尝试过 https://github.com/flutter/flutter /issues/11426#issuecomment-414047398 但我想探索类似于备忘录的选项.

I have also tried https://github.com/flutter/flutter/issues/11426#issuecomment-414047398 But i wanted to explore an option similar to memoizer.

有什么方法可以只获取一次数据(类似于备忘录)?

are there any alternatives to fetching data only once (something similar to memoizer)?

推荐答案

使用StatefulWidget，然后在State内创建一个Future变量(如_getTaskAsync).

Use StatefulWidget, then create an Future variable (like _getTaskAsync) inside State.

将gettask()分配给initState中的该将来变量.

Assign gettask() to that future variable in initState.

然后使用该变量作为FutureBuilder的参数(例如future: _getTaskAsync)

Then use that variable as argument to FutureBuilder(like future: _getTaskAsync)

代码:

class _MyStatefulWidgetState extends State<MyStatefulWidget> {

  Future _getTaskAsync;

  ...

  @override
  void initState() {
    _getTaskAsync = gettask();
    super.initState();
  }

  ...

    FutureBuilder(
      future: _getTaskAsync,
      builder: (context, snapshot) {
        if (snapshot.hasData) {
          //Stopwatch stopwatchbefore = new Stopwatch()..start();
          //print('futurebuilder executed in ${stopwatchbefore.elapsed}');

          return SingleChildScrollView(child: listViewWidget(snapshot.data));
        } else {
          return Center(child: CircularProgressIndicator());
        }
      },
    );

请参阅文档

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