enhanced_future_builder

Small FutureBuilder wrapper to improve readabiltity. It can also be used as an easy solution to the common 'my FutureBuilder keeps refiring' problem (more info about that here).

Stop FutureBuilder from refiring

Let's say you want to build an app that displays a random cat from the internet at launch and then increases a counter whenever a button is clicked. You came up with the following code:

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text('Clicked $_counter times')
    ),
    body: FutureBuilder(
      // resolves to cat data from the internet
      future: widget._api.getRandomCat(),
      builder: (context, snapshot) {
        if (snapshot.connectionState == ConnectionState.done) {
          // builds an image widget containing a random cat
          return _showCatWidget(snapshot.data);
        }else {
          return Center(child: Text('Loading...'));
        }
      }
    ),
    floatingActionButton: FloatingActionButton(
      // _incrementCounter calls setState() to update the view
      onPressed: _incrementCounter,
      tooltip: 'Increment',
      child: Icon(Icons.add),
    ),
  );
}

Which results in the following app:

As you can see there's a problem. Whenever the button is clicked, a new cat is shown to the user. This is not what we want and can be solved by using EnhancedFutureBuilder. Import the package and change the code to:

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text('Clicked $_counter times')
    ),
    body: EnhancedFutureBuilder(
      future: widget._api.getRandomCat(),
      // this is where the magic happens
      rememberFutureResult: true,
      whenDone: (dynamic cat) => _showCatWidget(cat),
      whenNotDone: Center(child: Text('Loading...')),
    ),
    floatingActionButton: FloatingActionButton(
      onPressed: _incrementCounter,
      tooltip: 'Increment',
      child: Icon(Icons.add),
    ),
  );
}

As you can see the code is a little easier to read now and the result will be just how we want it to be:

Usage

Ironically, EnhancedFutureBuilder doesn't require a builder anymore.

FutureBuilder:

FutureBuilder(
  future: _futureToResolve(),
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.done) {
      return MyWidget(snapshot.data);
    }else if (snapshot.connectionState == ConnectionState.waiting){
      return Center(child: Text('Waiting...'));
    }
    }else if (snapshot.connectionState == ConnectionState.active){
      return Center(child: Text('Active...'));
    }
    // ...
  }
}

EnhancedFutureBuilder:

EnhancedFutureBuilder(
  future: _futureToResolve(),
  rememberFutureResult: false,
  whenDone: (dynamic data) => MyWidget(data),
  whenWaiting: Center(child: Text('Waiting...')),
  whenActive: Center(child: Text('Active...')),
  // whenNone: ...
),

Libraries

enhanced_future_builder