如何使用底部导航条在两个页面之间传递数据

Question

我是新手。我使用底部导航栏，但我不知道如何从底部导航栏页面传递数据到主页，因为主页期待1个参数。我在其他页面之间传递数据，但我找不到一种方法来传递底部导航栏和主页之间的数据。任何帮助都将不胜感激提前感谢

这是我的导航页代码

import 'package:chat_app/models/user_model.dart';
import 'package:chat_app/screens/call_log_screen.dart';
import 'package:chat_app/screens/chat_screen.dart';
import 'package:chat_app/screens/home_screen.dart';
import 'package:chat_app/screens/search_screen.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
class CustomBottomNavigationBar extends StatefulWidget {
UserModel user;
CustomBottomNavigationBar(this.user);
@override
_CustomBottomNavigationBarState createState() =>
_CustomBottomNavigationBarState();
}
class _CustomBottomNavigationBarState extends State<CustomBottomNavigationBar> {
int _selectedIndex = 0;
late final screens = [
HomeScreen(widget.user),
CallLog(),
CallLog(),
CallLog(),
];
void onTapped(int index) {
print(widget.user.name);
setState(() {
_selectedIndex = index;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: screens[_selectedIndex],
bottomNavigationBar: BottomNavigationBar(
backgroundColor: Colors.black,
selectedIconTheme: IconThemeData(color: Colors.blue),
currentIndex: 2,
items: [
BottomNavigationBarItem(
icon: Icon(
CupertinoIcons.settings,
color: Colors.grey,
),
label: 'hi',
),
BottomNavigationBarItem(
icon: Icon(
CupertinoIcons.home,
color: Colors.grey,
),
label: 'hi',
),
BottomNavigationBarItem(
icon: Icon(
CupertinoIcons.phone,
color: Colors.grey,
),
label: 'hi',
),
BottomNavigationBarItem(
icon: Icon(
CupertinoIcons.chat_bubble_text,
color: Colors.grey,
),
label: 'hi',
),
],
onTap: onTapped,
),
);
}
}

这是我的主页代码

import 'package:cached_network_image/cached_network_image.dart';
import 'package:chat_app/models/user_model.dart';
import 'package:chat_app/screens/chat_screen.dart';
import 'package:chat_app/screens/search_screen.dart';
import 'package:chat_app/widgets/bottom_navigation_bar.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:intl/intl.dart';
import 'auth_screen.dart';
class HomeScreen extends StatefulWidget {
UserModel user;
HomeScreen(this.user);
@override
_HomeScreenState createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
@override
void initState() {
// TODO: implement initState
super.initState();
WidgetsBinding.instance!.addObserver(this);
setStatus('online');
}
void setStatus(String status) async {
await FirebaseFirestore.instance
.collection('users')
.doc(widget.user.uid)
.update({"userStatus": status});
}
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
// TODO: implement didChangeAppLifecycleState
if (state == AppLifecycleState.resumed) {
//online
setStatus("online");
} else {
//offline
setStatus('offline');
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Home'),
centerTitle: true,
backgroundColor: Colors.deepPurple,
actions: [
IconButton(
onPressed: () async {
await GoogleSignIn().signOut();
await FirebaseAuth.instance.signOut();
setStatus('offline');
Navigator.pushAndRemoveUntil(
context,
MaterialPageRoute(
builder: (context) => AuthScreen(),
),
(route) => false);
},
icon: Icon(Icons.logout),
),
],
),
body: StreamBuilder(
stream: FirebaseFirestore.instance
.collection('users')
.doc(widget.user.uid)
.collection('messages')
.snapshots(),
builder: (context, AsyncSnapshot snapshot) {
if (snapshot.hasData) {
if (snapshot.data.docs.length < 1) {
return Center(
child: Text('No Chat Available!!!'),
);
}
return ListView.builder(
itemCount: snapshot.data.docs.length,
itemBuilder: (context, index) {
var friendId = snapshot.data.docs[index].id;
var lastMsg = snapshot.data.docs[index]['last_message'];
var lastMsgTime =
snapshot.data.docs[index]['last_message_time'];
return FutureBuilder(
future: FirebaseFirestore.instance
.collection('users')
.doc(friendId)
.get(),
builder: (context, AsyncSnapshot asyncSnapShot) {
if (asyncSnapShot.hasData) {
var friend = asyncSnapShot.data;
return ListTile(
leading: ClipRRect(
borderRadius: BorderRadius.circular(80.0),
child: CachedNetworkImage(
imageUrl: friend['image'],
placeholder: (context, url) =>
CircularProgressIndicator(),
errorWidget: (context, url, error) =>
Icon(Icons.error),
),
// child: Image.network(
//   friend['image'],
// ),
),
trailing: Text(
DateFormat.jm().format(
lastMsgTime.toDate(),
),
),
title: Text(
friend['name'],
),
subtitle: Text(
"$lastMsg",
style: TextStyle(color: Colors.grey),
overflow: TextOverflow.ellipsis,
),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => ChatScreen(
currentUser: widget.user,
receiverId: friend['uid'],
receiverImage: friend['image'],
receiverName: friend['name'],
),
),
);
},
);
}
return LinearProgressIndicator();
},
);
},
);
}
return Center(
child: CircularProgressIndicator(),
);
},
),
floatingActionButton: FloatingActionButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => SearchScreen(widget.user),
),
);
// Navigator.pushAndRemoveUntil(
//     context,
//     MaterialPageRoute(
//       builder: (context) => SearchScreen(widget.user),
//     ),
//     (route) => false);
},
child: Icon(CupertinoIcons.search),
),
bottomNavigationBar: CustomBottomNavigationBar(widget.user),
);
}
}

Answer 1

不能在初始化器中访问实例成员widget

试试这个

class _CustomBottomNavigationBarState extends State<CustomBottomNavigationBar> {
int _selectedIndex = 0;
late final List screens;
@override
void initState() {
super.initState();
screens = [
HomeScreen(widget.user),
CallLog(),
CallLog(),
CallLog(),
];
}
...
// the rest of your code