How to access Shared Preferences String in build method flutter

Question

I'm trying to access userEmail in shared preferences, inside my build method. Here's some of the code for context:

  Widget build(BuildContext context) {
    final prefs = await SharedPreferences.getInstance();
    final userEmail = prefs.getString('userEmail') ?? '';
...
Return Scaffold(
body: SingleChildScrollView(
                scrollDirection: Axis.horizontal,
                child: StreamBuilder<QuerySnapshot>(
                  stream: _firestore.collection(userEmail).orderBy('time', descending: false).snapshots(),
...

The issue I have is, an error comes up highlighting the await. When i hover over it with my cursor for more info, it say The await expression can only be used in an async function. Try marking the function body with either 'async' or 'async*'.

There is then an option to add 'async' modifier. So i clicked that, which transformed code into this:

Future<Widget> build(BuildContext context) async {
...

This causes another error message: '_HomeScreenState.build' ('Future<Widget> Function(BuildContext)') isn't a valid override of 'State.build' ('Widget Function(BuildContext)').

Any ideas how to solve this issue? I've tried saving the userEmail using the Provider package. This works perfectly when the user first signs in or registers, but if you hot reload, the stream doesn't work.

Answer 1

As @croxx5f and @AhmetKAYGISIZ suggested, I ended up using FutureBuilder to solve this problem. Thank you both so much for your help with this.

Here's the final code for anyone else who is stuck on this problem:

class MyWidget extends StatefulWidget {


  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  var prefs;

  @override
  void initState() {
    super.initState();
    getUserEmailFromSharedPrefs();
  }

Future<String> getUserEmailFromSharedPrefs() async {
    prefs = await SharedPreferences.getInstance();
    final userEmail = prefs.getString('userEmail') ?? '';
    return userEmail;
  }

  @override
  Widget build(BuildContext context) {

    return FutureBuilder(
                future: getUserEmailFromSharedPrefs(),
                builder: (context, AsyncSnapshot<String> snapshot) {
                  if(snapshot.hasData) {
                   return SingleChildScrollView(
                     scrollDirection: Axis.horizontal,
                     child: StreamBuilder<QuerySnapshot>(
                       stream: _firestore.collection(snapshot.data).orderBy('time', descending: false).snapshots(),
...

So in summary, I wrapped my streambuilder in a futurebuilder.