Flutter for BottomModalSheet小部件中未找到Scaffold的错误，即使在Scaffold中定义了它也是如此 [英] Scaffold not found error in Flutter for BottomModalSheet widget even when it is defined inside a Scaffold

问题描述

我正在尝试为测试应用程序实现BottomModalSheet.但是每次弹出相同的错误消息时都说找不到Scaffold.该应用的代码如下.该错误表明该脚手架是由MaterialApp窗口小部件实现的，因此我删除了MaterialApp窗口小部件并进行了尝试，但再次弹出相同的错误.

I was trying to implement a BottomModalSheet for a test App. But every time the same error pops up saying that Scaffold not found. The code for the app is below. The error shows the Scaffold is implemented by the MaterialApp Widget, So I removed the MaterialApp Widget and tried but the same error popped up again.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Scaffold(
      appBar: AppBar(
        title: Text("Hello,World"),
      ),
      body: Center(
        child: Container(
          height: 300,
          width: 400,
          child: Column(
            children: <Widget>[
              //Container(color: Colors.blue, child: Text("Hello,World")),
              Container(
                height:200,
                width:500,
                child: FlatButton(
                  onPressed: (){
                    print("I Was clicked");
                    var sheetController = showBottomSheet(
                        context: context,
                        builder: (context) => BottomSheetWidget());
                    sheetController.closed.then((value) {
                    });
                  },
                  child: Container(
                    color: Colors.red,
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}


class BottomSheetWidget extends StatefulWidget {
  const BottomSheetWidget({Key key}) : super(key: key);

  @override
  _BottomSheetWidgetState createState() => _BottomSheetWidgetState();
}

class _BottomSheetWidgetState extends State<BottomSheetWidget> {
  @override
  Widget build(BuildContext context) {
    return Container(
      margin: const EdgeInsets.only(top: 5, left: 15, right: 15),
      height: 160,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        mainAxisSize: MainAxisSize.max,
        children: <Widget>[
          Container(
            height: 125,
            decoration: BoxDecoration(
                color: Colors.white,
                borderRadius: BorderRadius.circular(15),
                boxShadow: [
                  BoxShadow(
                      blurRadius: 10, color: Colors.grey[300], spreadRadius: 5)
                ]),
            child: Column(
              children: <Widget>[
                Container(
                  height:200,
                  width: 500,
                  child:Text("This is bottom Sheet")
                ),
              ],
            ),
          )
        ],
      ),
    );
  }
}

错误日志如下:

Syncing files to device AOSP on IA Emulator...
Reloaded 1 of 478 libraries in 2,727ms.
I/flutter (31983): I Was clicked

════════ Exception caught by gesture ═══════════════════════════════════════════════════════════════
The following assertion was thrown while handling a gesture:
No Scaffold widget found.

MyHomePage widgets require a Scaffold widget ancestor.
The specific widget that could not find a Scaffold ancestor was: MyHomePage
  state: _MyHomePageState#d2d59
The ancestors of this widget were: 
  : MaterialApp
    state: _MaterialAppState#d6736
  : MyApp
  ...

Typically, the Scaffold widget is introduced by the MaterialApp or WidgetsApp widget at the top of your application widget tree.

When the exception was thrown, this was the stack: 
#0      debugCheckHasScaffold.<anonymous closure> (package:flutter/src/material/debug.dart:112:7)
#1      debugCheckHasScaffold (package:flutter/src/material/debug.dart:123:4)
#2      showBottomSheet (package:flutter/src/material/bottom_sheet.dart:534:10)
#3      _MyHomePageState.build.<anonymous closure> (package:flutter_app/main.dart:42:43)
#4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:706:14)
...
Handler: "onTap"
Recognizer: TapGestureRecognizer#6c46a
  debugOwner: GestureDetector
  state: possible
  won arena
  finalPosition: Offset(169.5, 356.2)
  finalLocalPosition: Offset(163.8, 124.4)
  button: 1
  sent tap down
════════════════════════════════════════════════════════════════════════════════════════════════════

推荐答案

您可以在
下复制粘贴运行完整代码 您可以使用var scaffoldKey.currentState.showBottomSheet

You can copy paste run full code below
You can use var scaffoldKey.currentState.showBottomSheet

代码段

final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();

return Scaffold(
  key: scaffoldKey,

 ...

 onPressed: () {
                print("I Was clicked");
                var sheetController = scaffoldKey.currentState
                    .showBottomSheet((context) => BottomSheetWidget());
                sheetController.closed.then((value) {
                  print("closed");
                });
              },

工作演示

完整代码

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();

    return Scaffold(
      key: scaffoldKey,
      appBar: AppBar(
        title: Text("Hello,World"),
      ),
      body: Center(
        child: Container(
          height: 300,
          width: 400,
          child: Column(
            children: <Widget>[
              //Container(color: Colors.blue, child: Text("Hello,World")),
              Container(
                height: 200,
                width: 500,
                child: FlatButton(
                  onPressed: () {
                    print("I Was clicked");
                    var sheetController = scaffoldKey.currentState
                        .showBottomSheet((context) => BottomSheetWidget());
                    sheetController.closed.then((value) {
                      print("closed");
                    });
                  },
                  child: Container(
                    color: Colors.red,
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class BottomSheetWidget extends StatefulWidget {
  const BottomSheetWidget({Key key}) : super(key: key);

  @override
  _BottomSheetWidgetState createState() => _BottomSheetWidgetState();
}

class _BottomSheetWidgetState extends State<BottomSheetWidget> {
  @override
  Widget build(BuildContext context) {
    return Container(
      margin: const EdgeInsets.only(top: 5, left: 15, right: 15),
      height: 160,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        mainAxisSize: MainAxisSize.max,
        children: <Widget>[
          Container(
            height: 125,
            decoration: BoxDecoration(
                color: Colors.white,
                borderRadius: BorderRadius.circular(15),
                boxShadow: [
                  BoxShadow(
                      blurRadius: 10, color: Colors.grey[300], spreadRadius: 5)
                ]),
            child: Column(
              children: <Widget>[
                Container(
                    height: 100,
                    width: 500,
                    child: Text("This is bottom Sheet")),
              ],
            ),
          )
        ],
      ),
    );
  }
}

这篇关于Flutter for BottomModalSheet小部件中未找到Scaffold的错误，即使在Scaffold中定义了它也是如此的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！