[FIXED] How to get shared prefernces in build context

Issue

i am using flutter to make a widget AppBar Drawer and i saved datas in SharedPReferences... this is my Drawer.dart: class AppDrawer extends StatefulWidget {

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

class _AppDrawerState extends State<AppDrawer> {
  SharedPreferences prefs;

  Future<void> logOut() async {
    final prefs = await SharedPreferences.getInstance();

    prefs.clear();
    Navigator.pushReplacementNamed(
      context,
      '/login',
    );
  }

  @override
  Widget build(BuildContext context) {
    final deviceSize = MediaQuery.of(context).size;
    return Drawer(
      child: ListView(
        children: <Widget>[
          DrawerHeader(
            child: Text(prefs.getString('first_name')),
            decoration: BoxDecoration(
              color: Colors.red,
            ),
          ),
          ListTile(
            leading: Text('LogOut'),
            onTap: logOut,
          ),
        ],
      ),
    );
  }
}

the way i am using it to logout is working to clear them but when i want to use it in the widget build it give me a null response... i am trying to prefs.getString('first_name') but its giving me null :( what i am doing wrong here??

Solution

You need to implement it like.

class _AppDrawerState extends State<AppDrawer> {
  
  String name = "";
  SharedPreferences prefs;

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

  getName() async {
    final prefs = await SharedPreferences.getInstance();
    setState((){
      name = prefs.getString('first_name');
    });
  }

  Future<void> logOut() async {
    prefs.clear();
    Navigator.pushReplacementNamed(
      context,
      '/login',
    );
  }

  @override
  Widget build(BuildContext context) {
    final deviceSize = MediaQuery.of(context).size;
    return Drawer(
      child: ListView(
        children: <Widget>[
          DrawerHeader(
            child: Text(this.name),
            decoration: BoxDecoration(
              color: Colors.red,
            ),
          ),
          ListTile(
            leading: Text('LogOut'),
            onTap: logOut,
          ),
        ],
      ),
    );
  }
}

await SharedPreferences.getInstance(); is an async call, you can't make an async call inside initState method or build widget method. So, that I created a separate function to get preferences and then updated the state variable name.

Answered By - Ehtisham Shahid Abbasi

Answer Checked By - Senaida (PHPFixing Volunteer)