小编Aya*_*isy的帖子

此屏幕是一个抽屉屏幕，它采用身份验证块，以便为用户提供信息并使其能够注销。虽然我使用了正确的提供程序，但我收到了这个错误

The following ProviderNotFoundError was thrown building Pets4allDrawer(dirty):
I/flutter (32011): Error: Could not find the correct Provider<AuthService> above this Pets4allDrawer Widget
I/flutter (32011): To fix, please:
I/flutter (32011):   * Ensure the Provider<AuthService> is an ancestor to this Pets4allDrawer Widget
I/flutter (32011):   * Provide types to Provider<AuthService>
I/flutter (32011):   * Provide types to Consumer<AuthService>
I/flutter (32011):   * Provide types to Provider.of<AuthService>()
I/flutter (32011):   * Ensure the correct `context` is being used. 

我想知道为什么使用 Provider.of(context) 不起作用的问题，调用它时找不到它。

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:pets4all/blocs/authBloc.dart';
import …

在这段代码中，我试图在页面的顶部列出按钮或图块的列表，“因为按钮对我而言不合适”。因此，当单击一个时，它将在页面的其余部分返回一个值。

问题是：这里的图块在页面的一半以上扭曲，从而使其看起来不一致。我想限制瓷砖的高度，我尝试将它们放在一个行和一个容器中，但它不起作用。任何帮助将不胜感激。

运行代码后的结果是：

这是运行代码后的错误：

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

  @override
  HomePageState createState() {
    return new HomePageState();
  }
}

class HomePageState extends State<HomePage> {
List<String> temp=new List();
List<String> temp1=['Nile University', 'Smart Village', 'Zewail'];
Map<String,String> map1={};
@override
void initState() {
    super.initState();
  getplaces(temp);
  getuser(map1,'1jKpg81YCO5PoFOa2wWR');

  }


Future<List> getuser(temp,String place) async{
  List<String> userids=[];
  QuerySnapshot usersubs= await  Firestore.instance.collection('tempSubs').getDocuments();
  QuerySnapshot userid= await  Firestore.instance.collection('users').where('place',isEqualTo: place).getDocuments();
  userid.documents.forEach((DocumentSnapshot doc,){
  usersubs.documents.forEach((DocumentSnapshot doc1){
    if(doc.documentID==doc1.documentID){
      doc1.data['products'].forEach((k,v){

       if( DateTime.fromMillisecondsSinceEpoch(v).day==DateTime.now().day){

        int x= DateTime.fromMillisecondsSinceEpoch(v).day;
                print('keey equal $k and v …

在此小部件中，如果有问题，选项卡会在类型之间导航，它会进入指定的屏幕。如果是论坛，则会转到另一个论坛。问题是我需要将当前点击的类型传递给浮动操作按钮中的按下功能。然而浮动操作按钮位于脚手架主体之外。有没有办法将值传递给浮动操作按钮？

class TabScreen extends StatelessWidget {

  final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState();
  @override
  Widget build(BuildContext context) {
    final bool showfab = MediaQuery.of(context).viewInsets.bottom == 0.0;
    final AuthService authService = Provider.of<AuthService>(context);
 return StreamBuilder<List<String>>(
              stream: forumServices.forumsTypes$,
              builder: (context, snapshot) {
                if (!snapshot.hasData) {
                  return CircularProgressIndicator();
                }
                List<String> types = snapshot.data;
                num tabLen = types.length;

                return DefaultTabController(
                    length: tabLen,
                    child: Scaffold(
                      key: _scaffoldKey,

                      body: CustomScrollView(slivers: <Widget>[
                        SliverAppBar(
                          title: Text("kdkdkkd"),
                          bottom: TabBar(
                              tabs: types.map((String f) {
                            return Text(f);
                          }).toList()),
                        ),
                        SliverFillRemaining(
                          child: StreamBuilder<List<Forums>>(
                              stream: forumServices.forums$, …

我想知道在setState不为变量设置新值的情况下调用背后的要点。

  readLocal() async {
    prefs = await SharedPreferences.getInstance();
    id = prefs.getString('id') ?? '';
    if (id.hashCode <= peerId.hashCode) {
      groupChatId = '$id-$peerId';
    } else {
      groupChatId = '$peerId-$id';
    }

    setState(() {});
  }

通过单击showBottomSheet弹出导航到另一屏幕的屏幕时，以下代码引发此错误。我不明白为什么会这样。

class _CheckoutButtonState extends State<_CheckoutButton> {
  final GlobalKey<ScaffoldState> _globalKey = GlobalKey();
  final DateTime deliveryTime = DateTime.now().add(Duration(minutes: 30));

  final double deliveryPrice = 5.00;

  @override
  Widget build(BuildContext context) {
    SubscriptionService subscriptionService =
        Provider.of<SubscriptionService>(context);
    CheckoutService checkoutService = Provider.of<CheckoutService>(context);
    return Container(
      height: 48.0,
      width: MediaQuery.of(context).size.width * 0.75,
      child: StreamBuilder(
        stream: subscriptionService.subscription$,
        builder: (_, AsyncSnapshot<Subscription> snapshot) {
          if (!snapshot.hasData) {
            return Text("CHECKOUT");
          }
          final Subscription subscription = snapshot.data;
          final List<Order> orders = subscription.orders;
          final Package package = subscription.package;
          num discount = _getDiscount(package);
          num price = …

在尝试获取 SHA 证书指纹时，我运行了这一行，这就是结果行：

keytool -list -v -keystore %USERPROFILE%\.android\debug.keystore -alias androiddebugkey -storepass android -keypass android 

我还应该做什么来解决这个错误？

C:\>keytool -list -v -keystore %USERPROFILE%\.android\debug.keystore -alias androiddebugkey -storepass android -keypass android
Illegal option:  sisy\.android\debug.keystore
keytool -list [OPTION]...

Lists entries in a keystore

Options:

 -rfc                    output in RFC style
 -alias <alias>          alias name of the entry to process
 -keystore <keystore>    keystore name
 -cacerts                access the cacerts keystore
 -storepass <arg>        keystore password
 -storetype <type>       keystore type
 -providername <name>    provider name
 -addprovider <name>     add security provider by name …