sleeyax/enhanced_future_builder

This library is no longer maintained. Use at your own discretion.

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).

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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:

I love cats

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:

yeah cats are great

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: ...
),