How to use sharedpreference with sparkline, in flutter?

Question

Hello I tried to make a dynamic chart with sparkline, but I can't use my double variable from sharedpreference... when I use double variable I have an error : only static membre can be accessed in initializer. But I search to draw a dynamic chart not a static.

thank you

example :

 load_my_variable_double() async {


    SharedPreferences prefs = await SharedPreferences.getInstance();
    setState(() {
      my_variable_double= (prefs.getDouble('my_variable_double'))??0;

    });
  }

     var data = [my_variable_double,];  //only static membre can be accessed in initializer.
...    

       Sparkline
                            (
                            data: data,
                            lineWidth: 5.0,
                            lineColor: Colors.greenAccent,
                          )

Answer 1

try the following, it should work

 var data;
 load_my_variable_double() async {


    SharedPreferences prefs = await SharedPreferences.getInstance();
    setState(() {
      my_variable_double= (prefs.getDouble('my_variable_double'))??0;
      data = [my_variable_double,];

    });
  }


...    

       Sparkline
                            (
                            data: data,
                            lineWidth: 5.0,
                            lineColor: Colors.greenAccent,
                          )