【发布时间】：2021-01-18 12:27:51
【问题描述】：
我正在尝试从我的 onPressed() 函数中名为“PostAd”的另一个屏幕导航到我的“MainScreen”。但我收到布尔值不能为空的错误。当我单击错误时，它会将我带到“/mainScreen”这一行上的“HomePage”类：(context) => MainScreen()。很久以来我一直在尝试解决这个问题。任何帮助，将不胜感激。谢谢
Class PostAd{
@override
Widget build(BuildContext context) {
return Scaffold(
// backgroundColor: Colors.grey[600],
key: _scaffoldKey,
body: Container(
// decoration: BoxDecoration(
// image: DecorationImage(
// image: AssetImage("assets/background.png"),
// fit: BoxFit.cover,
// ),
// ),
padding: EdgeInsets.all(16.0),
child: Form(
child: ListView(
shrinkWrap: true,
children: <Widget>[
Center(
child: Text(
"Post New Ad",
style: TextStyle(fontSize: 30, fontWeight: FontWeight.bold),
),
),
AddPost(),
Padding(
padding: EdgeInsets.fromLTRB(0, 0, 0, 16),
),
], //:TODO: implement upload pictures
),
),
),
);
}
Widget AddPost(){
return Form(
key: _key,
autovalidate: _validate,
child: Padding(
padding: const EdgeInsets.fromLTRB(0.0, 20.0, 0.0, 0.0),
child:Column(
children: <Widget>[
_getPropertyTypeDropDown(),
_getPropertyTypeDetailDropDown(),
_selectedpropertyDetailType=='House'? _showExpansionList(): _selectedpropertyDetailType=='Flat'? _showExpansionList():_selectedpropertyDetailType=='Upper Portion'? _showExpansionList():_selectedpropertyDetailType=='Lower Portion'? _showExpansionList():_selectedpropertyDetailType=='Farm House'? _showExpansionList(): _selectedpropertyDetailType=='Residential Plot'? _showExpansionListPlot():_selectedpropertyDetailType=='Commercial Plot'? _showExpansionListPlot():_selectedpropertyDetailType=='Agricultural Plot'? _showExpansionListPlot(): _selectedpropertyDetailType=='Office'? _showExpansionListCommercial(): _selectedpropertyDetailType=='Shop'? _showExpansionListCommercial(): _selectedpropertyDetailType=='Ware House'? _showExpansionListCommercial(): _selectedpropertyDetailType=='Factory'? _showExpansionListCommercial():_selectedpropertyDetailType=='Building'? _showExpansionListCommercial(): _selectedpropertyDetailType=='Other'? _showExpansionListCommercial():_hideExpansionList(),
UploadPropertyImages(),
//ReadImagesFromFirebaseStorage(),
//_uploadImagesInput(),
//_showSelectImages(),
//_showAddImages(),
Container(
margin: EdgeInsets.only(left: 7),
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
//buildGridView(),
Container(
width: 200,
height: 200,
//color: Colors.green,
child: buildGridView(),
),
RaisedButton(
child: Text("Submit"),
onPressed: () {
if(_key.currentState.validate()){
_key.currentState.save();
showAlert("Post is Uploading. Please Wait ");
runMyFutureGetImagesReference();
Navigator.pushNamed(context, '/mainScreen');
}
else{
setState(() {
_validate = true;
});
}
// Navigator.pushNamed(context, '/mainScreen');
// setState(() {
// isButtonPressed7 = !isButtonPressed7;
// });
},
textColor: Colors.black,
padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
splashColor: Colors.grey,
),
],
),
),
Class MainScreen{
class MainScreen extends StatefulWidget {
final bool isAdmin;
const MainScreen({Key key, this.isAdmin}) : super(key: key);
@override
_MainScreenState createState() => _MainScreenState(this.isAdmin);
}
class _MainScreenState extends State<MainScreen> {
bool isPressed = false;
bool userLoggedIn =false;
//var _userName;
// Future<FirebaseUser> getUser() {
// return _auth.currentUser();
// }
Future<String> currentUser() async {
user = await _auth.currentUser();
return user != null ? user.uid : null;
}
FirebaseUser user;
@override
void initState() {
super.initState();
initUser();
}
String userid;
initUser() async {
user = await _auth.currentUser();
if (user != null) {
userid = user.uid;
} else {
print("user.uid");
// User is not available. Do something else
}
setState(() {});
}
bool isAdmin = true;
final FirebaseAuth _auth = FirebaseAuth.instance;
//final authData = snapshot.data;
_MainScreenState(this.isAdmin);
}
Class HomePage{
class HomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return ChangeNotifierProvider(
create: (context) => CurrentUser(),
child: MaterialApp(
debugShowCheckedModeBanner: false,
home: MainScreen(isAdmin: false,),
routes: {
'/main': (context) => HomePage(),
'/home': (context) => RoleCheck(),
ActivityFeed.routeName: (context) => ActivityFeed(),
//'/myProfileFinal': (context) => MyProfileFinal(),
MyProfileFinal.routeName: (ctx) => MyProfileFinal(),
ImageCarousel.routeName: (ctx) => ImageCarousel(),
// Random.routeName: (ctx) => Random(),
'/UserProfile': (context) => UserProfile(),
'/mainScreen': (context) => MainScreen(),
'/mainScreenUser': (context) => MainScreenUsers(),
'/LoginScreen': (context) => LoginPage(),
'/MyProfile': (context) => MyProfile(),
'/Signup': (context) => SignUpPage(),
'/ViewAdds': (context) => ViewAdds(),
'/PostDetail': (context) =>PostDetail(),
'/postscreen1': (context) => PostFirstScreen(),
'/choseOnMap':(context) => ChoseOnMap(),
'/AgentSignup': (context) => AgentSignUp(),
'/ForgetPassword': (context) => ForgetPassword(),
'/ImageCarousel': (context) => ImageCarousel(),
'/AgentSignup': (context) => AgentSignUp(),
'/ForgetPassword': (context) => ForgetPassword(),
},
),
);
}
}
【问题讨论】：
-
您希望
isAdmin具有什么价值？如果你导航到/mainScreen，它目前为空。 -
您应该发送 isAdmin 参数，因为它为空。或使用条件检查 isAdmin 是否为空。
标签： flutter