get Document from a string stored in variable using Firebase

get Document from a string stored in variable using Firebase - firebase

Here is my code
return await Firestore.instance.collection('RestaurantData').getDocuments('this.widget.restaurantName');
What should I place to access the passed data from the previous screen instead of ' this.widget.restaurantName' to receive the document from firebase in fluttter.

If you are passing data from one screen to another then you can do the following:
First Screen:
class FirstRoute extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('First Route'),
),
body: Center(
child: RaisedButton(
child: Text('Open route'),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute(resturantName : "Easy Meal")),
);
},
),
),
);
}
}
Here we pass resturantName property to SecondRoute, then in the next Screen you can do:
class SecondRoute extends StatefulWidget {
final String resturantName;
SecondRoute({this.resturantName});
#override
_SecondRouteState createState() => _SecondRouteState();
}
class _SecondRouteState extends State<SecondRoute> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.resturantName),
),
body: Center(
child: RaisedButton(
onPressed: () {
Navigator.pop(context);
},
child: Text('Go back!'),
),
),
);
}
}
using widget.resturantName you can access the value in the next screen.

Related

No MediaQuery widget ancestor found. All the answers on the service did not help (((

Making a list with adding items to the database. After switching from main.dart to the page with a list, it does not open, it writes an error.enter image description here
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
class Home extends StatefulWidget {
const Home({Key? key}) : super(key: key);
#override
State<Home> createState() => _HomeState();
}
class _HomeState extends State<Home> {
late String _userToDo;
List todoList = [];
void initFirebase() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
runApp(Home());
}
#override
void initState() {
super.initState();
initFirebase();
todoList.addAll(['Milk', 'Car', 'Sugar']);
}
void _menuOpen() {
Navigator.of(context).push(
MaterialPageRoute(builder: (BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Menu'),),
body: Row(
children: [
Padding(padding: EdgeInsets.only(left: 15)),
ElevatedButton(onPressed: () {
Navigator.pop(context);
Navigator.pushNamedAndRemoveUntil(context, '/', (route) => false);
},
child: Text('Home')),
Padding(padding: EdgeInsets.only(left: 15)),
Text('Home old')
],
)
);
})
);
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.grey[900],
appBar: AppBar(
title: Text('Список дел'),
actions: [
IconButton(onPressed: _menuOpen,
icon: Icon(Icons.menu_outlined),
)
],
),
body: ListView.builder(
itemCount: todoList.length,
itemBuilder: (BuildContext context, int index){
return Dismissible(
key: Key(todoList[index]),
child: Card(
child: ListTile(
title: Text(todoList[index]),
trailing: IconButton(
icon: Icon(Icons.delete_sweep,
color: Colors.redAccent,
), onPressed: () {
setState(() {
todoList.removeAt(index);
});
},
)
),
),
onDismissed: (direction) {
// if(direction == DismissDirection.startToEnd)
setState(() {
todoList.removeAt(index);
});
},
);
}
),
floatingActionButton: FloatingActionButton(
backgroundColor: Colors.green,
onPressed: () {
showDialog(context: context, builder: (BuildContext context){
return AlertDialog(
title: Text('Добавить'),
content: TextField(
onChanged: (String value){
_userToDo = value;
},
),
actions: [
ElevatedButton(onPressed: (){
FirebaseFirestore.instance.collection('items').add({'item': _userToDo});
Navigator.of(context).pop();
}, child: Text('Добавить')
)
],
);
});
},
child: Icon(Icons.add_comment_outlined,
color: Colors.white,
),
),
);
}
}
Everyone knows the error.
The following assertion was thrown building Home(state:
_HomeState#17f50): No MediaQuery widget ancestor found.
Scaffold widgets require a MediaQuery widget ancestor. The specific
widget that could not find a MediaQuery ancestor was: Scaffold dirty
state: ScaffoldState#4d9ee(lifecycle state: initialized, tickers:
tracking 2 tickers) The ownership chain for the affected widget is:
"Scaffold ← Home ← [root]"
No MediaQuery ancestor could be found starting from the context that
was passed to MediaQuery.of(). This can happen because you have not
added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets
introduce a MediaQuery), or it can happen if the context you use comes
from a widget above those widgets.
Set according to your advice. Navigation and pop-up window stopped working.
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
class Home extends StatefulWidget {
const Home({Key? key}) : super(key: key);
#override
State<Home> createState() => _HomeState();
}
class _HomeState extends State<Home> {
late String _userToDo;
List todoList = [];
void initFirebase() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
runApp(Home());
}
#override
void initState() {
super.initState();
initFirebase();
todoList.addAll(['Milk', 'Car', 'Sugar']);
}
void _menuOpen() {
Navigator.of(context).push(
MaterialPageRoute(builder: (BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Menu'),),
body: Row(
children: [
Padding(padding: EdgeInsets.only(left: 15)),
ElevatedButton(onPressed: () {
Navigator.pop(context);
Navigator.pushNamedAndRemoveUntil(context, '/', (route) => false);
},
child: Text('Home')),
Padding(padding: EdgeInsets.only(left: 15)),
Text('Home old')
],
)
);
})
);
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
backgroundColor: Colors.grey[900],
appBar: AppBar(
title: Text('Список дел'),
actions: [
IconButton(onPressed: _menuOpen,
icon: Icon(Icons.menu_outlined),
)
],
),
body: ListView.builder(
itemCount: todoList.length,
itemBuilder: (BuildContext context, int index){
return Dismissible(
key: Key(todoList[index]),
child: Card(
child: ListTile(
title: Text(todoList[index]),
trailing: IconButton(
icon: Icon(Icons.delete_sweep,
color: Colors.redAccent,
), onPressed: () {
setState(() {
todoList.removeAt(index);
});
},
)
),
),
onDismissed: (direction) {
// if(direction == DismissDirection.startToEnd)
setState(() {
todoList.removeAt(index);
});
},
);
}
),
floatingActionButton: FloatingActionButton(
backgroundColor: Colors.green,
onPressed: () {
showDialog(context: context, builder: (BuildContext context){
return AlertDialog(
title: Text('Добавить'),
content: TextField(
onChanged: (String value){
_userToDo = value;
},
),
actions: [
ElevatedButton(onPressed: (){
FirebaseFirestore.instance.collection('items').add({'item': _userToDo});
Navigator.of(context).pop();
}, child: Text('Добавить')
)
],
);
});
},
child: Icon(Icons.add_comment_outlined,
color: Colors.white,
),
),
),
);
}
}
The following assertion was thrown while handling a gesture: No
MaterialLocalizations found.
Home widgets require MaterialLocalizations to be provided by a
Localizations widget ancestor. The material library uses Localizations
to generate messages, labels, and abbreviations.
To introduce a MaterialLocalizations, either use a MaterialApp at the
root of your application to include them automatically, or add a
Localization widget with a MaterialLocalizations delegate.
The specific widget that could not find a MaterialLocalizations
ancestor was: Home state: _HomeState#8899d The ancestors of this
widget were: : [root]
renderObject: RenderView#1dbbb

void initFirebase() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
runApp(Home());
}
With that runApp call, you are removing your entire widget tree and replacing it with a tree rooted at a Home widget. This means that you are unable to access the MaterialApp widget that is presumably built by your App widget elsewhere in your app.
To fix this, move the first two lines of this method to your main method before runApp, and remove the entire method from the Home widget.

Part of the error says: This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget.
So in your Build method, you can wrap your Scaffold with a MaterialApp() and it should work.
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(...),
);
}

Flutter: Saving the state of a page even after navigating between screens

I have a simple thing to achieve. I have 2 screens in my app, on the main screen i have a button which navigates me to a new page called Interests. The Interests page is a list of checkboxes(for which i have to use listview.builder only) and a button to submit the data(which navigates me back to the main screen). The thing i want to achieve is this:
checkboxes should work properly.
when i navigate from Interests page to the main page and again navigate back to the Interests page, the selected checkboxes should remain checked. In short the state of the page should be saved.
I have written a function "applyInterestChanges" to save the data in database. I have to retrieve the same data to display the selected checkboxes(which we were doing by passing the data via constructor).
Any help would be appreciated!!
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(),
debugShowCheckedModeBanner: false,
);
}
}
class MyHomePage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Center(
child: RaisedButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => Interests(),
),
);
},
child: Text("Click here!!"),
),
),
),
);
}
}
class Interests extends StatefulWidget {
final List<dynamic> selectedList;
final void Function(List<dynamic>) callback;
Interests(this.selectedList, this.callback);
#override
_InterestsState createState() => _InterestsState();
}
class _InterestsState extends State<Interests> {
Map<String, dynamic> _categories = {
"responseCode": "1",
"responseText": "List categories.",
"responseBody": [
{"category_id": "1", "category_name": "Movies"},
{"category_id": "2", "category_name": "Sports"},
{"category_id": "3", "category_name": "Food"},
{"category_id": "4", "category_name": "Music"},
{"category_id": "5", "category_name": "Others"},
],
"responseTotalResult": 5
};
void _onCategorySelected(bool selected, categoryName) {
if (selected == true) {
setState(() {
widget.selectedList.add(categoryName);
});
} else {
setState(() {
widget.selectedList.remove(categoryName);
});
}
widget.callback(widget.selectedList);
}
applyInterestChanges() { //function to save the changes in database.
Firestore.instance
.collection('my_users')
.document(currentUserModel.id)
.updateData({
"interests": widget.selectedList,
});
} //this code is working properly. Need to similar function to retrieve the data and display the updated interests list.
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("Interests"),
),
body: SingleChildScrollView(
child: Column(
children: [
Text(
"Select your interests: ",
style: TextStyle(fontSize: 20.0, fontWeight: FontWeight.bold),
),
ListView.builder(
physics: NeverScrollableScrollPhysics(),
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemCount: _categories['responseTotalResult'],
itemBuilder: (BuildContext context, int index) {
return CheckboxListTile(
controlAffinity: ListTileControlAffinity.leading,
value: widget.selectedList.contains(
_categories['responseBody'][index]['category_name']),
onChanged: (bool selected) {
_onCategorySelected(selected,
_categories['responseBody'][index]['category_name']);
},
title:
Text(_categories['responseBody'][index]['category_name']),
);
},
),
MaterialButton(
onPressed: () {
Navigator.pop(context);
applyInterestChanges();
},
child: Text("Submit"),
),
],
),
),
);
}
}

You can pass an empty list from the parent widget MyHomeWidget & update this list via callback from the Interests widget.
Next time, whenever you go back & navigate again to Interests widget, we will pass this updated list which saves the state of Interests widget. Hence, the checkboxes will be checked depending upon their values in the list.
Here is the implementation:
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(),
debugShowCheckedModeBanner: false,
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
List<dynamic> selectedList = [];
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Center(
child: RaisedButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => Interests(
selectedList,
(List<dynamic> updatedList) {
setState(() {
selectedList = updatedList;
});
}
),
),
);
},
child: Text("Click here!!"),
),
),
),
);
}
}
class Interests extends StatefulWidget {
Interests(this.selectedList, this.callback);
// Passing the list from parent widget i.e, MyHomeWidget
// Initially the list will be empty
// We will update the list in parent whenever checkboxes change
final List<dynamic> selectedList;
// Creating a callback function to save state(update list) in
// MyHomeWidget
final void Function(List<dynamic>) callback;
#override
_InterestsState createState() => _InterestsState();
}
class _InterestsState extends State<Interests> {
Map<String, dynamic> _categories = {
"responseCode": "1",
"responseText": "List categories.",
"responseBody": [
{"category_id": "1", "category_name": "Movies"},
{"category_id": "2", "category_name": "Sports"},
{"category_id": "3", "category_name": "Food"},
{"category_id": "4", "category_name": "Music"},
{"category_id": "5", "category_name": "Others"},
],
"responseTotalResult": 5
};
void _onCategorySelected(bool selected, categoryId) {
if (selected == true) {
setState(() {
widget.selectedList.add(categoryId);
});
} else {
setState(() {
widget.selectedList.remove(categoryId);
});
}
// Callback to save the updated selectedList to MyHomeWidget list
widget.callback(widget.selectedList);
}
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("Interests"),
),
body: SingleChildScrollView(
child: Column(
children: [
Text(
"Select your interests: ",
style: TextStyle(fontSize: 20.0, fontWeight: FontWeight.bold),
),
ListView.builder(
physics: NeverScrollableScrollPhysics(),
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemCount: _categories['responseTotalResult'],
itemBuilder: (BuildContext context, int index) {
return CheckboxListTile(
value: widget.selectedList.contains(
_categories['responseBody'][index]['category_id']),
onChanged: (bool selected) {
_onCategorySelected(selected,
_categories['responseBody'][index]['category_id']);
},
title:
Text(_categories['responseBody'][index]['category_name']),
);
},
),
RaisedButton(
onPressed: () {
Navigator.pop(context);
},
child: Text("Go back!!"),
),
],
),
),
);
}
}
Here is the method that you wanted to fetch from Firebase. I have used the updated class FirebaseFirestore. If you are using the older version of Firebase, then simply replace FirebaseFirestore with Firebase.
Future<void> fetchInterestChanges() async { //function to get the changes in database.
final DocumentSnapshot doc = await FirebaseFirestore.instance
.collection('my_users')
.document(currentUserModel.id)
.get();
final updatedList = doc.data();
print(updatedList);
}

You should mixin with class AutomaticKeepAliveClientMixin to save old widgets, for example: https://github.com/diegoveloper/flutter-samples/blob/master/lib/persistent_tabbar/page2.dart.
Or when not work:
You must save data checkbox to cache, for example in shared presences, etc.
When reopening the page, you call data from the cache
And when checked/not resave data to cache

How am i able to retrieve specific users data using StreamBuilder?

1) This is the view team/view roster screen. https://imgur.com/a/k63lQrt
class ViewTeamScreen extends StatelessWidget {
static const routeName = '/view-team';
const ViewTeamScreen({Key key}) : super(key: key);
#override
Widget build(BuildContext context) {
return StreamProvider<List<User>>.value(
value: DBService().getAllUsers,
child: Scaffold(
body: TeamList()
),
);
}
}
2) This is the team list code that displays all user data on the ViewTeamScreen and returns a TeamTile widget i created.
class TeamList extends StatefulWidget {
#override
_TeamListState createState() => _TeamListState();
}
class _TeamListState extends State<TeamList> {
#override
Widget build(BuildContext context) {
final users = Provider.of<List<User>>(context) ?? [];
//print(users);
return ListView.builder(
itemCount: users.length,
itemBuilder: (context, index) {
return TeamTile(
user: users[index],
);
},
);
3) This is the TeamTile, which returns ListViewBuilder for a team member once they sign up to the app.
class TeamTile extends StatelessWidget {
final User user;
TeamTile({this.user});
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.only(top: 8.0),
child: Card(
margin: EdgeInsets.fromLTRB(20, 6, 20, 0),
child: ListTile(
leading: CircleAvatar(
radius: 30.0,
backgroundColor: Colors.brown,
),
title: Text(
'${user.firstName}'
" "
'${user.lastName}', //how do i make the first letter of name always CAPS?
style: TextStyle(fontSize: 23, letterSpacing: 1.0),
),
trailing: Text(user.email),
subtitle: Text('+44 0000 000 000'),
onTap: () async {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => TeamDetailScreen(),
),
);
},
),
4) This is the team detail screen, once the user taps on the ListTile in the ViewTeamScreen, this page will apear. https://imgur.com/a/7tSUO1c
class TeamDetailScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
final user = Provider.of<User>(context);
return Scaffold(
appBar: AppBar(
title: Text('Employee Contact Info'),
),
body: StreamBuilder<User>(
stream: DBService(uid: user.uid).usersData,
builder: (context, snapshot) {
if (snapshot.hasData) {
User userData = snapshot.data;
return Column(children: <Widget>[
Expanded(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Text(
'Name: ${userData.firstName}'
" "
'${userData.lastName}\n'
'Email: ${userData.email}',
style: TextStyle(fontSize: (20)),
),
)),
]);
} else {
return Loading();

This is going to exclude StreamProvider and just use StreamBuilder. This concept is easy to understand, as all we are doing is passing the widget.index down to other Widgets as arguments.
1
class ViewTeamScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return StreamBuilder<List<User>>(
stream: DBService().getAllUsers,
builder: (context, snapshot) {
if (snapshot.hasData) {
List<User> userData = snapshot.data;
return Scaffold(body: TeamList(myData: userData));
} else {
return Loading();
}
});
}
}
2
class TeamList extends StatefulWidget {
final List<User> myData;
TeamList({this.myData});
#override
_TeamListState createState() => _TeamListState();
}
class _TeamListState extends State<TeamList> {
#override
Widget build(BuildContext context) {
return ListView.builder(
itemCount: widget.myData.length,
itemBuilder: (context, index) {
return TeamTile(
usersInfo: widget.myData[index],
);
},
);
}
}
3
class TeamTile extends StatelessWidget {
final User usersInfo;
TeamTile({this.usersInfo});
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.only(top: 8.0),
child: Card(
margin: EdgeInsets.fromLTRB(20, 6, 20, 0),
child: ListTile(
leading: CircleAvatar(
radius: 30.0,
backgroundColor: Colors.brown,
),
title: Text(
'${usersInfo.firstName}'
" "
'${usersInfo.lastName}', //how do i make the first letter of name always CAPS?
style: TextStyle(fontSize: 23, letterSpacing: 1.0),
),
trailing: Text(usersInfo.email),
subtitle: Text('+44 0000 000 000'),
onTap: () async {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => TeamDetailScreen(myDetails: usersInfo),
),
);
},
),
),
);
}
}
4
class TeamDetailScreen extends StatelessWidget {
final User myDetails;
TeamDetailScreen({this.myDetails});
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Column(children: <Widget>[
Expanded(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Text(
'Name: ${myDetails.firstName}'
" "
'${myDetails.lastName}\n'
'Email: ${myDetails.email}',
style: TextStyle(fontSize: (20)),
),
)),
]),
);
}
}

NoSuchMethodError: The getter data was called on null, receiver: null

I am trying to create a detail screen to display my Firebase data from the database, and show the image along with some text data including the number of items, date, and geolocation. Is there a way to determine why the data is returning null? The navigator should navigate to the DetailPage.
Here is my Main file -
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:wasteagram/pages/create_waste.dart';
import 'package:wasteagram/services/crud.dart';
import 'pages/create_waste.dart';
import 'pages/detail_screen.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Wasteagram - ',
theme: new ThemeData(
primarySwatch: Colors.deepOrange,
),
home: new MyHomePage(title: 'Wasteagram - '),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
CrudMethods crudMethods = new CrudMethods();
Stream wasteStream;
Widget WasteList() {
return Container(
child: wasteStream != null ? Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
StreamBuilder(
stream: wasteStream,
builder: (context, snapshot) {
return ListView.builder(
padding: EdgeInsets.symmetric(horizontal: 16),
itemCount: snapshot.data.documents.length,
shrinkWrap: true,
itemBuilder: (context, index){
return WidgetTile(
wastedate:
snapshot.data.documents[index].data['wastedate'],
wastenumber:
snapshot.data.documents[index].data['wastenumber']
);
});
},)
],
) : Container(
alignment: Alignment.center,
child: CircularProgressIndicator(),
),
);
}
void initState() {
super.initState();
crudMethods.getData().then((result) {
wasteStream = result;
});
}
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text(widget.title),
),
body: WasteList(),
floatingActionButton: new FloatingActionButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => CameraScreen())
);
},
child: new Icon(Icons.add),
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
);
}
}
class WidgetTile extends StatelessWidget {
String wastedate, wastenumber;
WidgetTile({#required this.wastedate, #required this.wastenumber});
#override
Widget build(BuildContext context) {
return ListTile(
title: Text(wastedate),
trailing: Text(wastenumber),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => DetailPage())
);
}
);
}
}
Here is my detail_screen.dart
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:wasteagram/data/firestore_service.dart';
class DetailPage extends StatefulWidget {
final DocumentSnapshot post;
DetailPage({this.post});
#override
_DetailPageState createState() => _DetailPageState();
}
class _DetailPageState extends State<DetailPage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.post.data["wastedate"])
),
body: Center(
child: Container(
child: Column(
children: <Widget> [
Image.network(widget.post.data["image"]),
Text(widget.post.data["wastedate"]),
Text(widget.post.data["wastenumber"]),
Text(widget.post.data["wastelocation"].toString()),
]
)
)
),
);
}
}

You are not passing DocumentSnapshot to Detail Page.
Try this:
Widget WasteList() {
return Container(
child: wasteStream != null ? Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
StreamBuilder(
stream: wasteStream,
builder: (context, snapshot) {
return ListView.builder(
padding: EdgeInsets.symmetric(horizontal: 16),
itemCount: snapshot.data.documents.length,
shrinkWrap: true,
itemBuilder: (context, index){
return WidgetTile(
wastedate:
snapshot.data.documents[index].data['wastedate'],
wastenumber:
snapshot.data.documents[index].data['wastenumber'],
post:
snapshot.data.documents[index]
);
});
},)
],
) : Container(
alignment: Alignment.center,
child: CircularProgressIndicator(),
),
);
}
class WidgetTile extends StatelessWidget {
String wastedate, wastenumber;
DocumentSnapshot post;
WidgetTile({#required this.wastedate, #required this.wastenumber,#required this.post});
#override
Widget build(BuildContext context) {
return ListTile(
title: Text(wastedate),
trailing: Text(wastenumber),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => DetailPage(post: post))
);
}
);
}
}

Flutter - Change back button from Navigation Bar

Good day,
I need to change the command from back button located on Navigation Bar on Android cellphones, like the imagem bellow?
I need to change the button to appear a message, "Do you really want to quit the application?".To confirm the user leave the program.
Anyone can help?
Thanks.

Use the WillPopScope widget to handle the back button action, example :
class TestingWidget extends StatefulWidget {
#override
TestingWidgetState createState() {
return new TestingWidgetState();
}
}
class TestingWidgetState extends State<TestingWidget> {
Future<bool> _onBackPressed(){
final alertDialog = AlertDialog(
content: Text("Do you really want to quit the application?"),
actions: <Widget>[
FlatButton(
child: Text('Yes'),
onPressed: () => Navigator.of(context).pop(),
),
FlatButton(
child: Text('No'),
onPressed: () => Navigator.of(context).pop(),
)
],
);
showDialog(
barrierDismissible: false,
context: context,
builder: (context) => alertDialog);
}
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: _onBackPressed,
child: Scaffold(
appBar: AppBar(),
body: Center(child: Text("Hello world"),),
),
);
}
}

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Flutter - Change back button from Navigation Bar

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