flutter - SimpleDialog Flutter 中的 Snackbar

Question

在我的 Simpledialog 中将 snackbar 添加到按下方法时，我遇到了下面的错误代码。[使用不包含脚手架的上下文调用的 Scaffold.of()。]

我想就如何提供正确的上下文来解决它征求你的意见。

import 'package:flutter/material.dart';



void main() {
  runApp(new MaterialApp(home: new AlertApp()));
}

class AlertApp extends StatefulWidget {
  @override
  _AlertAppState createState() => _AlertAppState();
}

class _AlertAppState extends State<AlertApp> {


  SimpleDialog _simdalog;

  void sDialog(){
    _simdalog = new SimpleDialog(
      title: new Text("Add To Shopping Cart"),
      children: <Widget>[
        new SimpleDialogOption(
          child: new Text("Yes"),
          onPressed: (){
            final snackBar = SnackBar(content: Text('Purchase Successful'));
            Scaffold.of(context).showSnackBar(snackBar);
          },
        ),
        new SimpleDialogOption(
          child: new Text("Close"),
          onPressed:() {Navigator.pop(context);},
        ),
      ],
    );
    showDialog(context: context, builder: (BuildContext context){
      return _simdalog;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: new Center(
        child: Column(
          mainAxisSize: MainAxisSize.max,
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
        new RaisedButton(
            child: new Text("Add to Shopping Cart [Simple]"),
            onPressed:(){
              sDialog();
            }),
          ],
        ),
      ),
    );
  }
}

Answer 1

解决方案 1:正如 Mazin Ibrahim 在评论 Scaffold.of() called with a context that does not contain a Scaffold 中提到的那样

final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
...
Scaffold(
  key: _scaffoldKey,
...
onPressed: () {

                      _scaffoldKey.currentState.showSnackBar(
                          SnackBar(
                            content: Text('Purchase Successful'),
                            duration: Duration(seconds: 3),
                          ));
              }

解决方案 2:使用包 flushbar，您还可以在顶部显示通知
Flushbar 链接:https://github.com/AndreHaueisen/flushbar
另一个使用 flushbar How to show snackbar after navigator.pop(context) in Flutter? 的建议

    Flushbar(
      title: "Hey Ninja",
      message: "Lorem Ipsum is simply dummy text of the printing and typesetting industry",
      flushbarPosition: FlushbarPosition.TOP,
      flushbarStyle: FlushbarStyle.FLOATING,
      reverseAnimationCurve: Curves.decelerate,
      forwardAnimationCurve: Curves.elasticOut,
      backgroundColor: Colors.red,
      boxShadows: [BoxShadow(color: Colors.blue[800], offset: Offset(0.0, 2.0), blurRadius: 3.0)],
      backgroundGradient: LinearGradient(colors: [Colors.blueGrey, Colors.black]),
      isDismissible: false,
      duration: Duration(seconds: 4),
      icon: Icon(
        Icons.check,
        color: Colors.greenAccent,
      ),
      mainButton: FlatButton(
        onPressed: () {},
        child: Text(
          "CLAP",
          style: TextStyle(color: Colors.amber),
        ),
      ),
      showProgressIndicator: true,
      progressIndicatorBackgroundColor: Colors.blueGrey,
      titleText: Text(
        "Hello Hero",
        style: TextStyle(
            fontWeight: FontWeight.bold, fontSize: 20.0, color: Colors.yellow[600], fontFamily: "ShadowsIntoLightTwo"),
      ),
      messageText: Text(
        "You killed that giant monster in the city. Congratulations!",
        style: TextStyle(fontSize: 18.0, color: Colors.green, fontFamily: "ShadowsIntoLightTwo"),
      ),
    )..show(context);