Develop Reference

Undefined name '_image'. Try correcting the name to one that is defined, or defining the name

Please help.
I'm trying to display the photo captured in 'Generated1Group1Widget1.dart' to 'GeneratedResultsWidget.dart'. However, 'main.dart' is having some errors.
GeneratedGroup1Widget1.dart
class GeneratedGroup1Widget1 extends StatefulWidget {
#override
_GeneratedGroup1Widget1State createState() => _GeneratedGroup1Widget1State();
}
class _GeneratedGroup1Widget1State extends State<GeneratedGroup1Widget1> {
XFile? _image;
Future _pickImage() async {
final imageSource = await showDialog<ImageSource>(
context: context,
builder: (context) => SimpleDialog(
title: const Text('Select Image Source'),
children: [
SimpleDialogOption(
onPressed: () => Navigator.pop(context, ImageSource.camera),
child: const Text('Camera'),
),
SimpleDialogOption(
onPressed: () => Navigator.pop(context, ImageSource.gallery),
child: const Text('Gallery'),
),
],
),
);
if (imageSource != null) {
final image = await ImagePicker().pickImage(source: imageSource);
setState(() {
_image = image;
});
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => GeneratedResultsWidget(image: _image),
),
);
}
}
#override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () => _pickImage(),
...
GeneratedResultsWidget.dart
class GeneratedResultsWidget extends StatelessWidget {
final XFile? image;
GeneratedResultsWidget({
required this.image,
});
#override
Widget build(BuildContext context) {
return Material(
child: ClipRRect(
...
main.dart
void main() {
runApp(food_classifierApp());
}
class food_classifierApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ScreenUtilInit(
designSize: Size(360, 640),
builder: (BuildContext context,child) => MaterialApp(
title: 'food-classifier',
theme: ThemeData(
primarySwatch: Colors.blue,
),
initialRoute: '/GeneratedHomepageWidget',
routes: {
'/GeneratedScanWidget': (context) => GeneratedScanWidget(),
'/GeneratedResultsWidget': (context) => GeneratedResultsWidget(image: _image),
'/GeneratedHomepageWidget': (context) => GeneratedHomepageWidget(),
'/GeneratedFoodlistWidget': (context) => GeneratedFoodlistWidget(),
},
),
);
}
}
Error
Undefined name '_image'.
Try correcting the name to one that is defined, or defining the name.
I already searched up google but I can't find answers to my question. Thanks in advance!

Where exactly you define _image variable in your food_classifierApp class?
You should use state management to access your image or ... in every where of your app

You need to create model to store your picked image file from GeneratedGroup1Widget1.
class AppModel {
String fileName;
AppModel(this.fileName);
}
Now you can call it from GeneratedGroup1Widget1
Navigator.pushNamed(context, '/GeneratedResultsWidget',
arguments: AppModel('your file or file name'));
And recieve it here
class GeneratedResultsWidget extends StatelessWidget {
const GeneratedResultsWidget({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
final args = ModalRoute.of(context)!.settings.arguments as AppModel;
return Scaffold(body: Center(child: Text(args.fileName)));
}
}
Route should be
routes: {
//***
'/GeneratedResultsWidget': (context) => GeneratedResultsWidget(),
//***
}

Sending data to other page with bloc cubit

My problem is this. I created cubit for 2 different pages. When I am on the first page, I can fill the list inside the 2nd page and I can read it from the log. However, when I go to the second page, the list I filled in from the previous page is still empty.
Main.dart
home:
MultiBlocProvider(
providers: [
BlocProvider(create: (_) => HomeCubit(PhotoService())),
BlocProvider(create: (_)=> FavoritesCubit())//Gerekiyor,homeviewda içerisindeki methoda erişmem gerekiyor
],
child: const HomeView())
HomeView.dart
where I run the function in favoritescubit and add it to the list
onTap: () {
BlocProvider.of<FavoritesCubit>(context).addFavorite(
context,
state.selectItem![index],
);
print(state.selectItem?[index].isSelected);
context.read<FavoritesCubit>().getAllFavorites();
// print("UI --- ${state.selectItem![index].isSelected}");
// context.read<FavoriteBloc>().add(
// AddFavorite(photoList, photoList.isSelected));
// print(" ispressed ${photoList.isSelected}");
},
FavoritesCubit.dart
class FavoritesCubit extends Cubit<FavoritesState> {
FavoritesCubit() : super(const FavoritesState());
final List<PhotoModel> favoriteList = <PhotoModel>[];
Future<void> getAllFavorites() async {
print("FavoriteList : ${favoriteList.length}");
emit(state.copyWith(favoriteList: favoriteList));
}
Future<void> addFavorite(
BuildContext context,
PhotoModel photo,
) async {
photo.isSelected = !photo.isSelected;
if (favoriteList.contains(photo) == false) {
favoriteList.add(photo);
emit(state.copyWith(
favoriteList: favoriteList, isFavorite: photo.isSelected));
print("${state.favoriteList!.length}asdasd");
} else if (favoriteList.contains(photo) == true) {
favoriteList.remove(photo);
emit(state.copyWith(
favoriteList: favoriteList, isFavorite: photo.isSelected));
print("${state.favoriteList!.length}asdasd");
}
FavoriteView.dart
class FavoriteView extends StatefulWidget {
const FavoriteView({Key? key}) : super(key: key);
#override
State<FavoriteView> createState() => _FavoriteViewState();
}
class _FavoriteViewState extends State<FavoriteView> {
#override
void initState() {
super.initState();
}
#override
Widget build(BuildContext context) {
return BlocProvider(
create: (context) => FavoritesCubit()..getAllFavorites(),
child: Scaffold(
appBar: AppBar(
title: const Text("Bloc Example"),
),
body: buildFavoriteList(context),
),
);
}
}
Widget buildFavoriteList(BuildContext context) {
return BlocConsumer<FavoritesCubit, FavoritesState>(
listener: (context, state) {
// TODO: implement listener
},
builder: (context, state) {
return ListView.builder(
itemCount: state.favoriteList?.length,
itemBuilder: (context, index) {
return GestureDetector(
onTap: (() {
// navigateToPostDetailPage(context, photos[index]);
}),
child: Padding(
padding: const EdgeInsets.all(10),
child: PhotoListTile(
isPressed: state.favoriteList![index].isSelected,
imageUrl: state.favoriteList![index].thumbnailUrl.toString(),
title: state.favoriteList![index].title.toString(),
url: state.favoriteList![index].url.toString(),
onTap: () {
// context.read<HomeCubit>().addFavorite(
// context,
// state.favoriteList![index],
// state.favoriteList![index].isSelected);
// context
// .read<FavoriteBloc>()
// .add(RemoveFavorite(photos[index]));
},
),
),
);
});
},
);

Okey, now with your added information about your FavoriteView it is clear what the problem is.
In your FavoriteView you create a new cubit, which is not the same as you created in the MultiBlocProvider. That is why it is always empty on your FavoriteView
create: (context) => FavoritesCubit()..getAllFavorites(), // This is the issue
Make sure that your FavoriteView is a child somewhere under your MultiBlocProvider and remove the creation of a new FavoritesCubit in that view. I.e. remove the BlocProvider in your FavoriteView

LateInitializationError error in firebase auth code in flutter [duplicate]

This is the middle part of the main that is expected to cause the error. If you are not logged in on the splash screen, this code goes to MyHomePage and logs in. If you are logged in, it goes to MainScreen and switches to the main screen of the app.
class SplashScreen extends StatefulWidget {
#override
_SplashScreenState createState() => _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
final FirebaseAuth auth = FirebaseAuth.instance;
final User? user = FirebaseAuth.instance.currentUser;
#override
void initState() {
super.initState();
_initUser().whenComplete((){
setState(() {});
});
}
_initUser() async {
if (auth.currentUser != null) {
Timer(
Duration(seconds: 2),
() => Navigator.of(context).pushAndRemoveUntil(
MaterialPageRoute(
builder: (context) =>
MainScreen(user!)),
(Route<dynamic> route) => false),
);
} else {
Timer(Duration(seconds: 1),
() => Navigator.of(context).pushAndRemoveUntil(
MaterialPageRoute(
builder: (context) =>
MyHomePage()),
(Route<dynamic> route) => false),
);
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text("Splash Screen"),
),
);
}
}
This is the MyHomePage widget that is passed when you are not logged in.
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key}) : super(key: key);
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: TextButton(
onPressed: (){
FirebaseService().signup(context);
},
child: Text('Google'),
),
)
);
}
}
class FirebaseService{
final FirebaseAuth auth = FirebaseAuth.instance;
final GoogleSignIn googleSignIn = GoogleSignIn();
Future<void> signup(BuildContext context) async {
final GoogleSignInAccount? googleSignInAccount = await googleSignIn.signIn();
if (googleSignInAccount != null) {
final GoogleSignInAuthentication googleSignInAuthentication =
await googleSignInAccount.authentication;
final AuthCredential authCredential = GoogleAuthProvider.credential(
idToken: googleSignInAuthentication.idToken,
accessToken: googleSignInAuthentication.accessToken);
// Getting users credential
UserCredential result = await auth.signInWithCredential(authCredential);
User? user = result.user;
if (user != null) {
Navigator.push(
context, MaterialPageRoute(builder: (context) => MainScreen(user)));
} // if result not null we simply call the MaterialpageRoute,
// for go to the HomePage screen
}
}
Future<void> signOutFromGoogle() async{
await googleSignIn.signOut();
await auth.signOut();
}
}
This is the content of the error
The following LateError was thrown building MainScreen(dirty, dependencies: [_InheritedProviderScope<Pro?>], state: _MainScreenState#d95a0):
LateInitializationError: Field '_instance#640075166' has not been initialized.
The relevant error-causing widget was:
MainScreen MainScreen:file:///F:/flutter%20project/good_man/lib/main.dart:75:25
When the exception was thrown, this was the stack:
Sorry, I forgot the mainscreen code. Below is the mainscreen code
class MainScreen extends StatefulWidget {
const MainScreen(this.user);
final User user;
#override
_MainScreenState createState() => _MainScreenState();
}
class _MainScreenState extends State<MainScreen> {
#override
Widget build(BuildContext context) {
final User user = widget.user;
final pro = Provider.of<Pro>(context);
return DefaultTabController(
length: 3,
child: Scaffold(
appBar: PreferredSize(
preferredSize: Size.fromHeight(60.0), // here the desired height
child: AppBar(
iconTheme: IconThemeData(color: Colors.black),
backgroundColor: pro.backColor_main,
elevation: 0.0,
centerTitle: true,
title: Text('aaa',
style: TextStyle(
fontFamily: 'Gugi',
fontSize: 20.sp,
color: Colors.black,
),),
),
),
drawer: Drawer(
child: ListView(
padding: EdgeInsets.zero,
children: [
DrawerHeader(
child: Text('Drawer Header'),
decoration: BoxDecoration(
color: Colors.white
),
),
ListTile(
title: Text('aaa'),
onTap: () {
Navigator.pop(context);
},
),
],
),
),
bottomNavigationBar: BottomBar(),
body: Stack(children: [
TabBarView(
children: [
MainTest(),
Text(''),
Main_User(user),
],
),
])),
);
}
}
Sorry for posting all the code. There is no part that uses late , but the error code is displayed as late, and I try to delete the caches and start

Actually error is in Initialisation of current user...
You have to understand Life cycle of stateful widget...
initState is not holding flow. it just initialise some some instance value...And you try to delay for 2 sec... So that's the issue.
Use FutureBuilder for _initUser() and when it fetch all data then proceed for the next screen.

Don't initialise the async task into the initState. Because of Flutter Life Cycle it can not await the flow...
For more about the lIfe Cycle please visit this:
Life Cycle of Widget
So Solution is...
Use the FutureBuilder for awaiting the widget....
class SplashScreen extends StatefulWidget {
#override
_SplashScreenState createState() => _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
final FirebaseAuth auth = FirebaseAuth.instance;
final User? user = FirebaseAuth.instance.currentUser;
_initUser() async {
if (auth.currentUser != null) {
Timer(
Duration(seconds: 2),
() => Navigator.of(context).pushAndRemoveUntil(
MaterialPageRoute(
builder: (context) =>
MainScreen(user!)),
(Route<dynamic> route) => false),
);
} else {
Timer(Duration(seconds: 1),
() => Navigator.of(context).pushAndRemoveUntil(
MaterialPageRoute(
builder: (context) =>
MyHomePage() ),
(Route<dynamic> route) => false),
);
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: FutureBuilder(
future: _initUser(),
builder: (context, snapshot) {
if(snapshot.hasData){
//You you finish the initialization
return Text("You Get the Data");
}
//Until the data get
return Center(child: Text("Splash Screen"),);
},
),
);
}
}

Navigate to a specific page in a specific tab Flutter

I am quite new to flutter and I am trying to implement navigation between different tabs.
I am using a CupertinoTabView because I need a parallel navigators and a specific history for each tab in my bottom bar.
My question is whether it is possible to switch from a child page of Tab1 to a child page of Tab2, and if so in which way.
In this image you can see my widget tree:
Class MyApp.dart
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
TabItem _currentTab = TabItem.tab1;
final Map<TabItem, GlobalKey<NavigatorState>> navigatorKeys = {
TabItem.tab1: GlobalKey<NavigatorState>(),
TabItem.tab1: GlobalKey<NavigatorState>(),
};
Map<TabItem, WidgetBuilder> get widgetBuilders {
return {
TabItem.tab1: (_) => Tab1(),
TabItem.tab2: Tab2(),
};
}
void _select(TabItem tabItem) {
if (tabItem == _currentTab) {
navigatorKeys[tabItem].currentState.popUntil((route) => route.isFirst);
} else {
setState(() => _currentTab = tabItem);
}
}
#override
Widget build(BuildContext context) {
return CupertinoScaffold(
currentTab: _currentTab,
onSelectTab: _select,
widgetBuilders: widgetBuilders,
navigatorKeys: navigatorKeys,
);
}
}
Class CupertinoScaffold.dart (contains CupertinoTabView)
class CupertinoScaffold extends StatelessWidget {
const CupertinoScaffold({
Key key,
#required this.currentTab,
#required this.onSelectTab,
#required this.widgetBuilders,
#required this.navigatorKeys,
}) : super(key: key);
final TabItem currentTab;
final ValueChanged<TabItem> onSelectTab;
final Map<TabItem, WidgetBuilder> widgetBuilders;
final Map<TabItem, GlobalKey<NavigatorState>> navigatorKeys;
#override
Widget build(BuildContext context) {
return CupertinoTabScaffold(
tabBar: CupertinoTabBar(
key: Key(Keys.tabBar),
items: [
BottomNavigationBarItem(title: Text('Tab1')),
BottomNavigationBarItem(title: Text('Tab2'))
],
onTap: (index) => onSelectTab(TabItem.values[index]),
),
tabBuilder: (context, index) {
final item = TabItem.values[index];
return CupertinoTabView(
navigatorKey: navigatorKeys[item],
builder: (context) => widgetBuilders[item](context),
onGenerateRoute: CupertinoTabViewRouter.generateRoute,
);
},
);
}
}
Class Tab1.dart
class Tab1 extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Tab1')),
body: Center(
child: Button(
child: Text(
'Open child tab1'
),
onPressed: () => Navigator.of(context).pushNamed('/tab1-child'),
),
),
);
}
}
Class CupertinoTabViewRouter.dart
class CupertinoTabViewRouter {
static Route generateRoute(RouteSettings settings) {
switch (settings.name) {
case '/tab1-child':
return CupertinoPageRoute<dynamic>(
builder: (_) => Tab1Child(),
settings: settings,
fullscreenDialog: true,
);
case '/tab2-child':
return CupertinoPageRoute<dynamic>(
builder: (_) => Tab2Child(),
settings: settings,
fullscreenDialog: true,
);
}
return null;
}
}
Class Tab1Child.dart
class Tab1Child extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('ChildTab1')),
body: Center(
child: Button(
child: Text(
'Open child tab2'
),
onPressed: () => //TODO!,
),
),
);
}
}

How to send and receive arguments between views in flutter

I'm trying to send data from a page to another in flutter project, tried all methods I found in another question but all failed, here is my code :
The first page :
Navigator.pushNamed(context, '/line_details', arguments: {'line':line,});
The second page:
class _LineDetailsState extends State<LineDetails> {
Map data = {};
#override
Widget build(BuildContext context) {
data = ModalRoute.of(context).settings.arguments;
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.deepPurple,
title: Text("$data"),
),
);
}
}
note: the line is a custom object created.
the error : always returns null, even when tried to send a single string as {"test": "test string"} it returns a null too

your Example is working fine
route in MaterialApp
routes: { "/line_details": (context) => LineDetails(), },
Push on FlatButton:
onPressed: () => Navigator.pushNamed(context, '/line_details', arguments: {'line':'test',}),
class LineDetails
class LineDetails extends StatefulWidget {
#override
_LineDetailsState createState() => _LineDetailsState();
}
class _LineDetailsState extends State<LineDetails> {
Map data = {};
#override
Widget build(BuildContext context) {
data = ModalRoute.of(context).settings.arguments;
print(data);
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.deepPurple,
title: Text("$data"),
),
);
}
}
with GestureDetector is also working
new GestureDetector(
onTap: () => Navigator.pushNamed(context, '/line_details', arguments: {'line':'test',}),
child: new Container(child: new Text("GestureDetector"),),
),

try this:
Navigator.push(
context,
LineDetailsState(
builder: (context) => LineDetailsState(
line: line
)))
and
class LineDetailsState extends StatefulWidget {
LineDetailsState(this.line);
Line line;
#override
_LineDetailsState createState() => _LineDetailsState();
}
class _LineDetailsState extends State<LineDetails> {
Map data = {};
#override
Widget build(BuildContext context) {
data = ModalRoute.of(context).settings.arguments;
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.deepPurple,
title: Text("$data"),
),
);
}
}
instead of "Line" replace it with name of your custom object

Your example looks proper one other thing you can try is typecast your argument
like below which help dart for linting. Note this is not related that you are getting null
class LineDetails extends StatefulWidget {
#override
_LineDetailsState createState() => _LineDetailsState();
}
class _LineDetailsState extends State<LineDetails> {
Map data = {};
#override
Widget build(BuildContext context) {
data = ModalRoute.of(context).settings.arguments as Map<String,object>;
print(data);
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.deepPurple,
title: Text("$data"),
),
);
}
}