No MediaQuery widget ancestor found. All the answers on the service did not help (((-CodePudding

Making a list with adding items to the database. After switching from main.dart to the page with a list, it does not open, it writes an error.enter image description here

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';

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


  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {

  late String _userToDo;
  List todoList = [];

  void initFirebase() async {
    WidgetsFlutterBinding.ensureInitialized();
    await Firebase.initializeApp();
    runApp(Home());
  }

  @override
  void initState() {
    super.initState();

    initFirebase();

    todoList.addAll(['Milk', 'Car', 'Sugar']);
  }

  void _menuOpen() {
    Navigator.of(context).push(
      MaterialPageRoute(builder: (BuildContext context) {
        return Scaffold(
          appBar: AppBar(title: Text('Menu'),),
          body: Row(
            children: [
              Padding(padding: EdgeInsets.only(left: 15)),
              ElevatedButton(onPressed: () {
                Navigator.pop(context);
                Navigator.pushNamedAndRemoveUntil(context, '/', (route) => false);
              },
                  child: Text('Home')),
              Padding(padding: EdgeInsets.only(left: 15)),
              Text('Home old')
            ],
          )
        );
      })
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.grey[900],
      appBar: AppBar(
        title: Text('Список дел'),
        actions: [
          IconButton(onPressed: _menuOpen,
              icon: Icon(Icons.menu_outlined),
          )
        ],
      ),
      body: ListView.builder(
          itemCount: todoList.length,
          itemBuilder: (BuildContext context, int index){
            return Dismissible(
                key: Key(todoList[index]),
                child: Card(
                  child: ListTile(
                    title: Text(todoList[index]),
                      trailing: IconButton(
                        icon: Icon(Icons.delete_sweep,
                        color: Colors.redAccent,
                        ), onPressed: () {
                          setState(() {
                            todoList.removeAt(index);
                          });
                      },
                      )
                  ),
                ),
              onDismissed: (direction) {
                //  if(direction == DismissDirection.startToEnd)
                    setState(() {
                      todoList.removeAt(index);
                    });
              },
             );
          }
       ),
        floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.green,
        onPressed: () {
        showDialog(context: context, builder: (BuildContext context){
          return AlertDialog(
          title: Text('Добавить'),
          content: TextField(
           onChanged: (String value){
             _userToDo = value;
        },
        ),
            actions: [
              ElevatedButton(onPressed: (){

                FirebaseFirestore.instance.collection('items').add({'item': _userToDo});

                Navigator.of(context).pop();
              }, child: Text('Добавить')
              )
            ],
          );
        });
    },
    child: Icon(Icons.add_comment_outlined,
    color: Colors.white,
    ),
    ),
    );
  }
}

Everyone knows the error.

The following assertion was thrown building Home(state: _HomeState#17f50): No MediaQuery widget ancestor found.

Scaffold widgets require a MediaQuery widget ancestor. The specific widget that could not find a MediaQuery ancestor was: Scaffold dirty state: ScaffoldState#4d9ee(lifecycle state: initialized, tickers: tracking 2 tickers) The ownership chain for the affected widget is: "Scaffold ← Home ← [root]"

No MediaQuery ancestor could be found starting from the context that was passed to MediaQuery.of(). This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.

CodePudding user response：

Part of the error says: This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget.

So in your Build method, you can wrap your Scaffold with a MaterialApp() and it should work.

@override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(...),
    );
}

CodePudding user response：

set according to your advice, navigation and pop-up window stopped working

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';

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


  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {

  late String _userToDo;
  List todoList = [];

  void initFirebase() async {
    WidgetsFlutterBinding.ensureInitialized();
    await Firebase.initializeApp();
    runApp(Home());
  }

  @override
  void initState() {
    super.initState();

    initFirebase();

    todoList.addAll(['Milk', 'Car', 'Sugar']);
  }

  void _menuOpen() {
    Navigator.of(context).push(
      MaterialPageRoute(builder: (BuildContext context) {
        return Scaffold(
          appBar: AppBar(title: Text('Menu'),),
          body: Row(
            children: [
              Padding(padding: EdgeInsets.only(left: 15)),
              ElevatedButton(onPressed: () {
                Navigator.pop(context);
                Navigator.pushNamedAndRemoveUntil(context, '/', (route) => false);
              },
                  child: Text('Home')),
              Padding(padding: EdgeInsets.only(left: 15)),
              Text('Home old')
            ],
          )
        );
      })
    );
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
      backgroundColor: Colors.grey[900],
      appBar: AppBar(
        title: Text('Список дел'),
        actions: [
          IconButton(onPressed: _menuOpen,
              icon: Icon(Icons.menu_outlined),
          )
        ],
      ),
      body: ListView.builder(
          itemCount: todoList.length,
          itemBuilder: (BuildContext context, int index){
            return Dismissible(
                key: Key(todoList[index]),
                child: Card(
                  child: ListTile(
                    title: Text(todoList[index]),
                      trailing: IconButton(
                        icon: Icon(Icons.delete_sweep,
                        color: Colors.redAccent,
                        ), onPressed: () {
                          setState(() {
                            todoList.removeAt(index);
                          });
                      },
                      )
                  ),
                ),
              onDismissed: (direction) {
                //  if(direction == DismissDirection.startToEnd)
                    setState(() {
                      todoList.removeAt(index);
                    });
              },
             );
          }
       ),

        floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.green,
        onPressed: () {
        showDialog(context: context, builder: (BuildContext context){
          return AlertDialog(
          title: Text('Добавить'),
          content: TextField(
           onChanged: (String value){
             _userToDo = value;
        },
        ),
            actions: [
              ElevatedButton(onPressed: (){

                FirebaseFirestore.instance.collection('items').add({'item': _userToDo});

                Navigator.of(context).pop();
              }, child: Text('Добавить')
              )
            ],
          );
        });
    },
    child: Icon(Icons.add_comment_outlined,
    color: Colors.white,
    ),
    ),
      ),
    );
  }
}

The following assertion was thrown while handling a gesture: No MaterialLocalizations found.

Home widgets require MaterialLocalizations to be provided by a Localizations widget ancestor. The material library uses Localizations to generate messages, labels, and abbreviations.

To introduce a MaterialLocalizations, either use a MaterialApp at the root of your application to include them automatically, or add a Localization widget with a MaterialLocalizations delegate.

The specific widget that could not find a MaterialLocalizations ancestor was: Home state: _HomeState#8899d The ancestors of this widget were: : [root] renderObject: RenderView#1dbbb