Flutter SnackBar 未显示

我已经实现了一个表单提交功能。我想在提交后有 SnackBar Alert。我已经尝试过，但不起作用。添加 SnackBar 路由后也不起作用。

addTicket() async {
if (_formKey.currentState.validate()) {
  _formKey.currentState.save();

  try{
    DocumentReference ref = await db.collection('CostalLineTicketDetails').
    document(ticketCato).collection("Tickets").add(
        {
          'startStation':startStation,
          'endStation':endStation,
          'price':price,
          'ticketType':ticketCato,
          'contactNo':contactNo,
          'dateTime':dateTime,
        });
    setState(() => id = ref.documentID);
    Navigator.push(context, new MaterialPageRoute(builder: (context) => CostalLine()));

    Scaffold.of(context).showSnackBar(SnackBar(content: Text('Ticket Added Sucessfully')));

  }catch(e){
    print(e);
  }
}

} }

1. 你无法显示showSnackBar转到另一个屏幕后在同一页面上。
2. 您可以声明_scaffoldKey 并将其传递给 Scaffold 像这样

final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();

Scaffold(
      key: _scaffoldKey,

然后像这样打开snackbar

_scaffoldKey.currentState.showSnackBar(SnackBar(
        content: Text(
         'Welcome',
        ),
        duration: Duration(seconds: 2),
      ));

Output:

Edit

您还可以使用flash https://pub.dev/packages/flash不需要经过的地方_scaffoldKey每次。

example:

   void _showBasicsFlash({
    Duration? duration,
    flashStyle = FlashBehavior.floating,
  }) {
    showFlash(
      context: context,
      duration: duration,
      builder: (context, controller) {
        return Flash(
          controller: controller,
          behavior: flashStyle,
          position: FlashPosition.bottom,
          boxShadows: kElevationToShadow[4],
          horizontalDismissDirection: HorizontalDismissDirection.horizontal,
          child: FlashBar(
            content: Text('This is a basic flash'),
          ),
        );
      },
    );
  }