文本小部件不得为 null

Question

I pass argument through a pushNamedandRemoveUntil but it shows text widget must not be null when I try to access the passed parameter.

CustomButton(
                    buttonText: 'Go',
                    buttonClick: () {Navigator.pushNamedAndRemoveUntil(context, Next.id, (route) => false, arguments: "123456789");},
                  ),

class Next extends StatefulWidget {

  const Next({this.number});
  static const id = "next";
  final String number;
  @override
  _NextState createState() => _NextState();
}

class _NextState extends State<Next> {
 @override
  Widget build(BuildContext context) {
       return Scaffold(
body: Container(child: Center(child: Text(widget.number)))
)
}
}

Error is Failed assertion: line 298 pos 10: 'data != null'

Answer 1

its because your passed parameter is null

and if you want to handle the error you should use Text widget like this:

Text(widget.number ?? '')

and you should pass parameter like this

CustomButton(
  buttonText: 'Go',
  buttonClick: () {
      navigator.pushAndRemoveUntil(
         MaterialPageRoute(builder: (BuildContext context) => Next(id: '123456789')),
        (Route<dynamic> route) => false,
      );
),

Answer 2

You can't access like that. Use ModalRoute in your next screen and fetch the data.

Widget build(BuildContext context) {
      final number = ModalRoute.of(context).settings.arguments as String;
//....
}