so i want to print user name and user username in the profile page and in the end it shows it but for a few seconds there is a red screen that says The following _TypeError was thrown building Profile_page(dirty, state: _Profile_pageState#68414): type 'Null' is not a subtype of type 'String'
this is the code of main.dart
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:gp1_7_2022/screen/auth/signup/userInfo/name.dart';
import 'package:gp1_7_2022/screen/auth/signup/Questions/question1.dart';
import 'package:gp1_7_2022/screen/auth/signup/Questions/question2.dart';
import 'package:gp1_7_2022/screen/auth/signup/Questions/question3.dart';
import 'package:gp1_7_2022/screen/auth/signup/Questions/question4.dart';
import 'package:gp1_7_2022/screen/auth/signup/Questions/question5.dart';
import 'package:gp1_7_2022/screen/auth/signup/userInfo/photo.dart';
import 'package:gp1_7_2022/screen/home/Profile_Page.dart';
import 'package:firebase_core/firebase_core.dart';
/*pages */
import 'package:gp1_7_2022/screen/auth/signup_login.dart';
import 'package:gp1_7_2022/screen/auth/signup/userAuth/signup.dart';
import 'package:gp1_7_2022/screen/auth/Login/login.dart';
import 'package:gp1_7_2022/screen/auth/signup/userAuth/signupConfirmationCode.dart';
import 'package:gp1_7_2022/screen/auth/signup/userAuth/signupPassword.dart';
import 'package:gp1_7_2022/screen/auth/signup/userInfo/signupBirthday.dart';
import 'package:gp1_7_2022/screen/auth/signup/userInfo/signupUsername.dart';
import 'package:gp1_7_2022/screen/auth/Login/forget_password.dart';
import 'package:gp1_7_2022/screen/settings.dart';
void main() async{
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
runApp(
MaterialApp(
initialRoute: "/",
routes: {
"/": (context) => MainPage(),
"/signup": (context)=> Signup(),
'/login':(context)=>Login(),
'/Profile_Page':(context) => Profile_page(uid: FirebaseAuth.instance.currentUser!.uid),
// '/confirmationCode':(context) => ConfirmationCode(),
// '/signupPassword':(context) => signupPassword(),
'/signupBirthday':(context) => SignupBirthday(),
'/signupUsername':(context) => SignupUsername(),
'/forget_password':(context) => forget_password(),
'/name':(context) => name(),
'/question1':(context) => question1(),
'/question2':(context) => question2(),
'/question3':(context) => question3(),
'/question4':(context) => question4(),
'/question5':(context) => question5(),
'/photo':(context) => Photo(),
'/settings':(context) => settings(),
}
)
);
}
class MainPage extends StatelessWidget {
const MainPage({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
body: StreamBuilder<User?>(
stream: FirebaseAuth.instance.authStateChanges(),
builder: (context, snapshot){
if(snapshot.connectionState==ConnectionState.waiting){
return const Center(child: CircularProgressIndicator());
}else if(snapshot.hasError){
return const Center(child: Text("Something went wrong!"));
}else if(snapshot.hasData){
if(FirebaseAuth.instance.currentUser!.emailVerified && FirebaseAuth.instance.currentUser!.uid != null ){
String uid = FirebaseAuth.instance.currentUser!.uid;
return Profile_page(uid: uid );
}else{
String? x = FirebaseAuth.instance.currentUser!.email;
String y= x??" ";
return ConfirmationCode(email: y);
}
} else{
return const Signup_Login();
}
},
),
);
}
}
this is the code of profile_page.dart
// import 'dart:html';
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:focused_menu/focused_menu.dart';
import 'package:focused_menu/modals.dart';
/*pages */
/*colors */
import 'package:gp1_7_2022/config/palette.dart';
import 'package:gp1_7_2022/Widgets/follow_button.dart';
import 'package:rflutter_alert/rflutter_alert.dart';
import 'package:gp1_7_2022/screen/settings.dart';
class Profile_page extends StatefulWidget {
final uid;
const Profile_page({Key? key, required this.uid}) : super(key: key);
@override
State<Profile_page> createState() => _Profile_pageState();
}
class _Profile_pageState extends State<Profile_page> {
var padding= 0.8;
var userData = {};
@override
void initState() {
super.initState();
getData();
}
/* get data method */
getData() async {
try {
if (widget.uid != null) {
var userSnap = await FirebaseFirestore.instance.collection('users').doc(
widget.uid).get();
userData = userSnap.data()!;
setState(() {
});
}
}
catch(e){
Alert(
context: context,
title: "Something went wrong!",
desc: e.toString(),
).show();
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Palette.backgroundColor,
appBar: AppBar(
//appBar style
elevation: 0,
backgroundColor: Palette.backgroundColor,
automaticallyImplyLeading: false,//no arrow
//username
title: Padding(
padding: EdgeInsets.fromLTRB(5, 0, 0, 0),
child: Text(
userData['username'],
style: TextStyle(
color: Colors.black,
fontWeight: FontWeight.bold,
fontSize: 24,
),
),
),
//setting icon
actions:[
FocusedMenuHolder(
//
menuWidth: MediaQuery.of(context).size.width * 0.4,
menuOffset: 0,
menuItemExtent: 49,
//list
menuItems: [
FocusedMenuItem(
title: const Text("Log out"),
trailingIcon: const Icon(Icons.logout),
onPressed: (){
/*go to sign up page*/
Navigator.pushNamed(context, '/');
return FirebaseAuth.instance.signOut();
}
),
FocusedMenuItem(
title: const Text("Settings"),
trailingIcon: const Icon(Icons.settings),
onPressed: (){
Navigator.of(context).popAndPushNamed('/settings');
},
),
],
openWithTap: true,
onPressed: (){},
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 24),
child: Image.asset(
"assets/menu-icon.png",
height: 25,
width: 25,
),
),
),
],
),
body: ListView(
children: [
Container(
margin: const EdgeInsets.all(16),
child: Column(
children: [
Row(
children: [
//user photo
const Padding(
padding: EdgeInsets.fromLTRB(0, 0, 40, 0),
child: CircleAvatar(
backgroundColor: Colors.white ,
child: Icon(
Icons.account_circle_sharp,
color: Colors.grey,
size: 90,
),
),
),
//end user photo
Expanded(
flex: 7,
child: Column(
children: [
SizedBox(height:40,),
//post, followers and following
Row(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
buildStatColumn(20, "posts"),
buildStatColumn(150, "Followers"),
buildStatColumn(10, "Following"),
],
),
//end post, followers and following
],
),
),
],
),
//username
Container(
alignment: Alignment.centerLeft,
padding: EdgeInsets.fromLTRB(10, 40, 0, 0),
child: Text(
userData['name'],
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 16,
),
),
),
//end of username
//bio
Container(
alignment: Alignment.centerLeft,
padding: const EdgeInsets.fromLTRB(10, 1, 0, 0),
child: const Text(
'bio',
style: TextStyle(
fontSize: 16,
),
),
),
//end of bio
//edit profile button
Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
// mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
FollowButton(
text: 'Edit profile',
backgroundColor: Palette.backgroundColor,
borderColor: Palette.grey,
textColor: Colors.black,
function: () {},
)
],
),
//end of button
],
),
),
],
),
);
}
}
// function to show following/followers/# of posts
Column buildStatColumn(int num, String label) {
return Column(
mainAxisSize: MainAxisSize.min,
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
num.toString(),
style: const TextStyle(
fontSize: 20,
fontWeight: FontWeight.bold,
),
),
Container(
margin: const EdgeInsets.only(top: 4),
child: Text(
label,
style: const TextStyle(
fontSize: 16,
fontWeight: FontWeight.w400,
color: Colors.grey,
),
),
),
],
);
}
CodePudding user response：
Show some other widgets until data is not fully loaded.
class _Profile_pageState extends State<Profile_page> {
...
bool _isloaded = false; // Add this boolean
In getData function
getData() async {
try {
...
setState(() {
_isloaded = true; // when data is loaded update state
});
}
...
In build, return widget according to data(user)
@override
Widget build(BuildContext context) {
return _isloaded == false ?
Center(
child: CircularProgressIndicator(), // Show indicator
)
: Scaffold(
backgroundColor: Palette.backgroundColor,
...
); //Scaffold
CodePudding user response：
You're assuring flutter that the data isn't null which will result in a momentary error. You can try either setting a load bool that sets to true when the data arrives or using the ?? operator. e.g userData['name'] ?? "loading" which will print loading incase the userData['name'] is null