sharedPrefrence get data only once flutter?-CodePudding

i am trying to get data to a screen by shared prefrences so i set data here on my login screen:

var displayName=jsondata["username"];
    SharedPreferences prefs=await SharedPreferences.getInstance();
    prefs.setString('displayName', displayName);

and getting this data on my drawer:

  String displayName="0";



  initState() {
   getData();
   super.initState();
  }
   getData() async {
   SharedPreferences prefs = await SharedPreferences.getInstance();
   displayName=prefs.getString('displayName')?? "0";
   }

**it gets the data when i click on drawer button but when go back to main screen and re-enter in my drawer it gets value "0" **here is the demo of issue

what is wrong?

and here is the code of the other screen which I move in between:

   late String displayName;
   getData() async {
   SharedPreferences prefs = await SharedPreferences.getInstance();
  displayName=prefs.getString('displayName')?? "0";
 print(displayName);
}
initState() {
  getData();
  super.initState();
  }

CodePudding user response：

first of all always use a method after super.initState(); inside initState. after that assuming that variable displayName is not updated anywhere else try to log when ever displayName changes in your code. I can see that another screen is opening and then he value changes. so please show us more code of what you write.

CodePudding user response：

Please refer to below code

String displayName="0";



  initState() {
   getData();
   super.initState();
  }
   getData() async {
   SharedPreferences prefs = await SharedPreferences.getInstance();
if(displayName.isEmpty || displayName == "0"){
   displayName=prefs.getString('displayName')?? "0";
await prefs.reload();
}
   }

CodePudding user response：

to Keep listening to code even you moved between pages,use StreamBuilder

StreamBuilder<DocumentSnapshot>(
                    stream:getData(),
                    builder: ( context, snapshot) {
                      if(snapshot.connectionState==ConnectionState.waiting){
                        return CircularProgressIndicator();
                      }else {

                        if(snapshot.hasData){
                       // .......

                        }
                       

                      }
                    }
                )