import 'package:flutter/material.dart';
import 'fruits_listing_card.dart';
import 'fruits_page.dart';
Map<String, Widget> fruits = {
"banana": FruitsListingCards(
fruitBGColor: 0xFFF8A8B5,
fruitImagePath: 'images/fruits/banana.png',
fruitName: 'Banana',
fruitPrice: 'Rs. 105',
fruitShortDescription: 'Ripe & Tasty',
onTap: () {
Navigator.push(context, MaterialPageRoute(builder: (context) => FruitsPage()),);
},
),
}
// Second File
import 'package:flutter/material.dart';
class FruitsPage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Container(),
),
);
}
}
Both the code are in different files.
FruitsListingCards is a widget that has a Gesture detector functionality. onTap is a parameter that takes function.
I am using FruitsListingCards in the main file and whenever a user taps on it, should go to the FruitsPage screen. But the error is not letting me to do so. Any solution with proper explanantion will help me a lot.
EDIT:
For proper understanding of code, check my repo:
https://github.com/RaghavTheGreat1/fruits_delivery/tree/master/lib
You have to provide context some how, so that it can connect the last screen and next screen.
You can wrap inside a function for that.
Following minimal code will help you more to understand.
class DeleteWidget extends StatefulWidget {
#override
_DeleteWidgetState createState() => _DeleteWidgetState();
}
class FruitsPage extends StatelessWidget {
final Function call;
FruitsPage({this.call});
#override
Widget build(BuildContext context) {
return Container(
child: RaisedButton(
child: Text("press"),
onPressed: call,
),
);
}
}
class NewPage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Container(
child: Text("FruiysPage"),
),
),
);
}
}
callme(context) {
Map<String, Widget> fruits = {
"banana": FruitsPage(
call: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => NewPage()),
);
},
)
};
return fruits;
}
Well, I figured out the problem on omy own and it was easier than what other people had suggested me even if they haven't looked into my code committed in my GitHub repo.
The quick solution or fix was to add Navigator.push(context, MaterialPageRoute(builder: (context) => fruitsPage)); inside the anonymous function of GestureDetector in FruitsListingCards and then returning fruitsPage(which is a dynamic variable that will take Class object as parameter).
Related
My final goal is to have a userName variable from one dart file transferred to the other dart file.
Firebase Authentication will only take the email and password inputs so I need to pass the userName variable as an argument into another file that is called after the users email has been verified.
I have been trying to find videos and documentation online, most of what I found is trying to put the data into a list (which I would like to avoid). I don't understand the "this." getter function in flutter yet, I don't know if it's necessary to solve this problem. Let me know if there's anything I can clarify, I hope I'm overlooking something simple.
Dart File #1
onPressed: () => signUp(_email, _password).then((_) {
Navigator.of(context).pushReplacement(
MaterialPageRoute(builder: (context) => Verify(_userName)));
}),
Dart File #2
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
class Verify extends StatefulWidget {
const Verify(String _userName, {Key? key}) : super(key: key);
#override
_VerifyState createState() => _VerifyState();
}
class _VerifyState extends State<Verify> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child:
Text('Here is your variable $_userName please verify'),
),
);
}
I guess you're asking about passing arguments(any object) between different screens.
You can do this easily by passing it in RouteSettings, you can pass any object (String, int, map) and then fetch it in the build method of another Screen.
class MyWidget extends StatelessWidget {
#override
Widget build(BuildContext context) {
return TextButton(
onPressed: () => Navigator.push(
context, MaterialPageRoute(
builder: (context) => HomeScreen(),
settings: const RouteSettings(arguments: 'username')),), //arguments
child: Text('Hello, World!',
style: Theme.of(context).textTheme.headline4,
),
);
}
}
class HomeScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
final args = ModalRoute.of(context)!.settings.arguments as String; //arguments
return TextButton(
onPressed: () {},
child: Text(args,
style: Theme.of(context).textTheme.headline4,
),
);
}
}
I receive some errors when I try to push my flutter page from neighbourhoodList to individual neighbourhoods (e.g. neighbourhoodlist_admirality).
In my neighbourhoodlist, I would like to navigate to the individual neighbourhood pages when the user has clicked on the relevant neighbourhood. As I have not build the individual neighbourhood pages yet, I have linked them to an example page i.e. NeighbourhoodAdmirality.
This is my code for the neighbourhoodlist page:
import 'package:flutter/material.dart';
import 'indv_neighbourhoods/neighbourhoodlist_admirality.dart';
class NeighbourhoodList extends StatefulWidget {
NeighbourhoodList({ this.name = "name"});
final String name;
#override
_NeighbourhoodListState createState() => _NeighbourhoodListState();
}
class _NeighbourhoodListState extends State<NeighbourhoodList> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(
'Neighbourhoods',
),
),
body: _buildListView(context),
);
}
ListView _buildListView(BuildContext context){
return ListView.builder(
itemCount: allNeighbourhoods.length,
itemBuilder: (BuildContext content, int index) {
NeighbourhoodList neighbourhoodlist = allNeighbourhoods[index];
return NeighbourhoodListTile(neighbourhoodlist);
});
}
}
class NeighbourhoodListTile extends ListTile {
NeighbourhoodListTile(NeighbourhoodList neighbourhoodlist)
: super(
title: Text(neighbourhoodlist.name),
trailing: Icon(Icons.arrow_forward),
onTap: (){
Navigator.push(
context,
MaterialPageRoute(builder: (context) => NeighbourhoodAdmiralty(neigh1)),
);
}
);
}
List<NeighbourhoodList> allNeighbourhoods = [
NeighbourhoodList(name: 'Admiralty'),
NeighbourhoodList(name: 'Aljunied'),
NeighbourhoodList(name: 'Ang Mo Kio'),
];
This is my code for an example page that I want to direct my neighbourhoodlist to when each individual neighbourhood is directed.
import 'package:flutter/material.dart';
class NeighbourhoodAdmiralty extends StatefulWidget {
final String neigh1;
NeighbourhoodAdmiralty(this.neigh1);
#override
_NeighbourhoodAdmiraltyState createState() => _NeighbourhoodAdmiraltyState();
}
class _NeighbourhoodAdmiraltyState extends State<NeighbourhoodAdmiralty> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Admiralty"),
),
body: Center(child: Text('This is the individual neighbourhood page'),
),
);
}
}
As I am still a beginner, I am facing some errors and have a few questions on these:
Error 1 on neighbourhoodlist.dart: "Undefined name 'context'" under Navigator.push --> not sure why this happens as I have already passed the BuildContext in my methods above
Error 2 on neighbourhoodlist.dart: "Undefined name 'neigh1'" under Navigator.push --> I would like to redirect the neighbourhoodlist.dart page to the individual neighbourhood sheets but I'm not sure what I pass here, I have tried 'neigh1' (my variable in neighbourhoodlist_admirality), 'name' - the variable in NeighbourhoodList, and 'index' 0 the variable inNeighbourhoodListState but none of them seem to work so far.
Appreciate all your help in resolving this and thanks in advance !
When you do
class NeighbourhoodListTile extends ListTile {
NeighbourhoodListTile(NeighbourhoodList neighbourhoodlist)
: super(
title: Text(neighbourhoodlist.name),
trailing: Icon(Icons.arrow_forward),
onTap: (){
Navigator.push(context, MaterialPageRoute(builder: (context) => NeighbourhoodAdmiralty(neigh1)));
}
);
}
you can't access context in onTap because Flutter hasn't yet provided one to you in this point. If you need the context, use a StatelessWidget instead, where you can access it in the build method:
class NeighbourhoodListTile extends StatelessWidget {
final NeighbourhoodList neighbourhoodlist;
const NeighbourhoodListTile(this.neighbourhoodlist);
#override
Widget build(BuildContext context) {
// Here's your context ^^^^^^^
return ListTile(
title: Text(neighbourhoodlist.name),
trailing: Icon(Icons.arrow_forward),
onTap: (){
Navigator.push(context, MaterialPageRoute(
builder: (context) => NeighbourhoodAdmiralty(neigh1)));
}
);
}
}
As to your second error, there is also no neigh1 variable at this point. I don't know what your logic is, but I think you want to replace it with neighbourhoodlist.name:
class NeighbourhoodListTile extends StatelessWidget {
final NeighbourhoodList neighbourhoodlist;
const NeighbourhoodListTile(this.neighbourhoodlist);
#override
Widget build(BuildContext context) {
return ListTile(
title: Text(neighbourhoodlist.name),
trailing: Icon(Icons.arrow_forward),
onTap: (){
Navigator.push(context, MaterialPageRoute(
builder: (context) => NeighbourhoodAdmiralty(neighbourhoodlist.name)));
}
);
}
}
The used Getx Arguments are cleared after the showDialog method is executed.
_someMethod (BuildContext context) async {
print(Get.arguments['myVariable'].toString()); // Value is available at this stage
await showDialog(
context: context,
builder: (context) => new AlertDialog(
//Simple logic to select between two buttons
); // get some Confirmation to execute some logic
print(Get.arguments['myVariable'].toString()); // Variable is lost and an error is thrown
Also I would like to know how to use Getx to show snackbars without losing the previous arguments as above.
One way to do this is to duplicate the data into a variable inside the controller and make a use from it instead of directly using it from the Get.arguments, so when the widget tree rebuild, the state are kept.
Example
class MyController extends GetxController {
final myArgument = ''.obs;
#override
void onInit() {
myArgument(Get.arguments['myVariable'] as String);
super.onInit();
}
}
class MyView extends GetView<MyController> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Expanded(
child: Center(child: Obx(() => Text(controller.myArgument()))),
),
);
}
}
UPDATE
Since you are looking for solution without page transition, another way to achieve that is to make a function in the Controller or directly assign in from the UI. Like so...
class MyController extends GetxController {
final myArgument = 'empty'.obs;
}
class MyView extends GetView<MyController> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Expanded(
child: ElevatedButton(
onPressed: () => _someMethod(context),
child: Obx(() => Text(controller.myArgument())),
),
),
);
}
void _someMethod(BuildContext context) async {
// store it in the state.
controller.myArgument(Get.arguments['myVariable'] as String);
await showDialog(
context: context,
builder: (context) => new AlertDialog(...),
);
print(controller.myArgument()); // This should work
}
}
UPDATE 2 (If you don't use GetView)
class MyController extends GetxController {
final myArgument = 'empty'.obs;
}
class MyView extends StatelessWidget {
final controller = Get.put(MyController());
#override
Widget build(BuildContext context) {
return Scaffold(
body: Expanded(
child: ElevatedButton(
onPressed: () => _someMethod(context),
child: Obx(() => Text(controller.myArgument())),
),
),
);
}
void _someMethod(BuildContext context) async {
// store it in the state.
controller.myArgument(Get.arguments['myVariable'] as String);
await showDialog(
context: context,
builder: (context) => new AlertDialog(...),
);
print(controller.myArgument()); // This should work
}
}
UPDATE 3 (NOT RECOMMENDED)
If you really really really want to avoid using Controller at any cost, you can assign it to a normal variable in a StatefulWidget, although I do not recommend this approach since it was considered bad practice and violates the goal of the framework itself and might confuse your team in the future.
class MyPage extends StatefulWidget {
const MyPage({ Key? key }) : super(key: key);
#override
_MyPageState createState() => _MyPageState();
}
class _MyPageState extends State<MyPage> {
String _myArgument = 'empty';
#override
Widget build(BuildContext context) {
return Scaffold(
body: Expanded(
child: ElevatedButton(
onPressed: () => _someMethod(context),
child: Text(_myArgument),
),
),
);
}
void _someMethod(BuildContext context) async {
// store it in the state.
setState(() {
_myArgument = Get.arguments['myVariable'] as String;
});
await showDialog(
context: context,
builder: (context) => new AlertDialog(...),
);
print(_myArgument); // This should work
}
}
We want to show an AlertDialog after some asynchronous processing such as network processes.
When calling 'showAlertDialog ()' from an external class, I want to call it without context. Is there a good way?
class SplashPage extends StatelessWidget implements SplashView {
BuildContext _context;
#override
Widget build(BuildContext context) {
this._context = context;
...
}
I've considered the above method, but I'm worried about side issues.
Help
My current code
class SplashPage extends StatelessWidget implements SplashView {
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: MyStoreColors.eats_white1_ffffff,
body: Center(
child: new SvgPicture.asset('assets/ic_splash.svg'),
),
);
}
#override
void showAlertDialog() {
showDialog<void>(
context: /*How to get context?*/,
builder: (BuildContext context) {
return AlertDialog(
title: Text('Not in stock'),
content: const Text('This item is no longer available'),
actions: <Widget>[
FlatButton(
child: Text('Ok'),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
}
#override
void moveToHomeContainer() {
}
#override
void moveToLoginContainer() {
}
}
To show an AlertDialog you need the context, but in StatelessWidget you do not have access to it directly as in StatefulWidget.
Few options are [1]:
passing it as GlobalKey [2]
passing build context as parameter to any other function inside StatelessWidget
use a service to inject the dialog without context [3]
Cheers.
You should trigger rebuild when the async event complete, either convert your widget to StatefulWidget and call setState() or use a state management solution like Bloc.
For example using StatefulWidget your code will look like this:
class SplashPage extends StatefulWidget {
#override
State<SplashPage> createState() => _SplashPageState();
}
class _SplashPageState extends State<SplashPage> implements SplashView {
bool _asynOpDone = false;
/// Call this when the async operation is done.
void _onAsynOpDone() => setState(() => _asyncOpDone = true);
#override
Widget build(BuildContext context) {
if (_asyncOpDone) showAlertDialog(context);
return Scaffold(
...,
///
);
}
#override
void showAlertDialog(BuildContext context) {
showDialog<void>(
context: context,
builder: ...,
);
}
}
You can apply Builder pattern concept to simplify this.
There is a little example here.
button_builder.dart
I am creating a loading screen for an app. This loading screen is the first screen to be shown to the user. After 3 seconds the page will navigate to the HomePage. everything is working fine. But when the user taps back button the loading screen will be shown again.
FIRST PAGE CODE
import 'dart:async';
import 'package:flutter/material.dart';
import 'home_page.dart';
void main() {
runApp(MaterialApp(
home: MyApp(),
));
}
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => new _MyAppState();
}
class _MyAppState extends State<MyApp> {
#override
void initState() {
super.initState();
Future.delayed(
Duration(
seconds: 3,
), () {
// Navigator.of(context).pop(); // THIS IS NOT WORKING
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => HomePage(),
),
);
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: FlutterLogo(
size: 400,
),
),
);
}
}
HOMEPAGE CODE
import 'package:flutter/material.dart';
class HomePage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Center(
child: Text('HomePage'),
),
),
);
}
}
I tried to add Navigator.of(context).pop(); before calling the HomePage but that is not working. This will show a blank black screen.
Any ideas??
You need to use pushReplacement rather than just push method. You can read about it from here: https://docs.flutter.io/flutter/widgets/Navigator/pushReplacement.html
And to solve your problem just do as explain below.
Simply replace your this code:
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => HomePage(),
),
);
with this:
Navigator. pushReplacement(
context,
MaterialPageRoute(
builder: (context) => HomePage(),
),
);
Yes, I found the same problem as you. The problem with replace is that it only works once, but I don't know why it doesn't work as it should. For this after a few attempts, I read the official guide and this method exists: pushAndRemoveUntil (). In fact, push on another widget and at the same time remove all the widgets behind, including the current one. You must only create a one Class to management your root atrough the string. This is the example:
class RouteGenerator {
static const main_home= "/main";
static Route<dynamic> generatorRoute(RouteSettings settings) {
final args = settings.arguments;
switch (settings.name) {
case main_home:
return MaterialPageRoute(builder: (_) => MainHome());
break;
}
}
}
This class must be add to the Main in:
MaterialApp( onGenerateRoute: ->RouteGenerator.generatorRoute)
Now to use this method, just write:
Navigator.of(context).pushNamedAndRemoveUntil(
RouteGenerator.main_home,
(Route<dynamic> route) => false
);