Flutter: How to fetch data from api only once while using FutureBuilder?

How can I fetch data only once while using FutureBuilder to show a loading indicator while fetching?

The problem is that every time the user opens the screen it will re-fetch the data even if I set the future in initState().

I want to fetch the data only the first time the user opens the screen then I will use the saved fetched data.

should I just use a stateful widget with a loading variable and set it in setState()?

I'm using Provider package

Future<void> fetchData() async {
try {
  final response =
      await http.get(url, headers: {'Authorization': 'Bearer $_token'});......

and my screen widget:

    class _MyScreenState extends State<MyScreen> {
  Future<void> fetchData;

  @override
  void initState() {

    fetchData =
        Provider.of<Data>(context, listen: false).fetchData();

    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: fetchData,
      builder: (ctx, snapshot) =>
          snapshot.connectionState == ConnectionState.done
              ? Consumer<Data>(
                  builder: (context, data, child) => Text(data.fetchedData)): Center(
                               child: CircularProgressIndicator(),
                               ),
                        
    );
  }
}

If you want to fetch the data only once even if the widget rebuilds, you would have to make a model for that. Here is how you can make one:

class MyModel{
 String value;
 Future<String> fetchData() async {
 if(value==null){
 try {
  final response =
      await http.get(url, headers: {'Authorization': 'Bearer $_token'});......
 value=(YourReturnedString)
  }
 }
  return value;
 }
}

Don't forget to place MyModel as a Provider. In your FutureBuilder:

@override
  Widget build(context) {
    final myModel=Provider.of<MyModel>(context)
    return FutureBuilder<String>(
      future: myModel.fetchData(),
      builder: (context, snapshot) {
        // ...
      }
    );
  }