How to fix WillPopScope() not working for me - android-studio

I created two pages one is login and main page but i want close app from main page i am using Willpopscope but it is not working for me i have tried all things but the onwillpop method is not calling please help me thank you.
class main_page extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(primarySwatch: Colors.amber),
home: my_page(),
);
}
}
class my_page extends StatefulWidget {
#override
_my_pageState createState() => _my_pageState();
}
class _my_pageState extends State<my_page> {
#override
void initState() {
check_login();
super.initState();
}
Future check_login() async {
SharedPreferences preferences = await SharedPreferences.getInstance();
if (preferences.getBool("islogin") == false)
setState(() {
Navigator.of(context).push(MaterialPageRoute(
builder: (context) => MyApp(),
));
});
}
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async=>false,
child: Scaffold(
appBar: new AppBar(
title: Text(
"Home",
style: new TextStyle(color: Colors.white),
),
actions: <Widget>[
FlatButton(
onPressed: () async {
SharedPreferences sharedPreferences =
await SharedPreferences.getInstance();
setState(() {
sharedPreferences.setBool("islogin", false);
Navigator.of(context).push(MaterialPageRoute(
builder: (context) => main_page(),
));
});
},
child: Text(
"Logout",
style: TextStyle(color: Colors.white, fontSize: 16.0),
))
],
),
),
);
}
}
I am also using Shredprefrences but i think it does not matter i want close app from my main_page please help me for this Thank you.

Just check out this answer and let me know if it works:
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:flutter/services.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(primarySwatch: Colors.amber),
home: SecondPage(),
);
}
}
class LoginPage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Center(
child: RaisedButton(
child: Text('Move to second page after Login'),
onPressed: () async {
SharedPreferences preferences =
await SharedPreferences.getInstance();
preferences.setBool("islogin", true);
// this will remove the login page after routing to the second page and then the stack will have only one page that is second page.
// so later you can use the willpopscape
Navigator.pushAndRemoveUntil(
context,
MaterialPageRoute(builder: (context) => SecondPage()),
ModalRoute.withName("/Home"));
},
)),
),
);
}
}
class SecondPage extends StatefulWidget {
#override
_SecondPageState createState() => _SecondPageState();
}
class _SecondPageState extends State<SecondPage> {
#override
void initState() {
check_login();
super.initState();
}
Future check_login() async {
SharedPreferences preferences = await SharedPreferences.getInstance();
if (preferences.getBool("islogin") == null)
//This above if statement will check if the parameter islogin is null then redirect to the login screeen
// else if the value is not null then i will not enter the if statement
setState(() {
Navigator.of(context).push(MaterialPageRoute(
builder: (context) => LoginPage(),
));
});
}
Future<bool> _onWillPop() async {
// This dialog will exit your app on saying yes
return (await showDialog(
context: context,
builder: (context) => new AlertDialog(
title: new Text('Are you sure?'),
content: new Text('Do you want to exit an App'),
actions: <Widget>[
new FlatButton(
onPressed: () => Navigator.of(context).pop(false),
child: new Text('No'),
),
new FlatButton(
onPressed: () => Navigator.of(context).pop(true),
child: new Text('Yes'),
),
],
),
)) ??
false;
}
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: _onWillPop,
child: Scaffold(
appBar: new AppBar(
title: Text(
"Home",
style: new TextStyle(color: Colors.white),
),
actions: <Widget>[
FlatButton(
onPressed: () async {
SystemNavigator.pop();
},
child: Text(
"Logout",
style: TextStyle(color: Colors.white, fontSize: 16.0),
))
],
),
),
);
}
}

Here is answer example_page code
class exmp extends StatefulWidget {
#override
_exmpState createState() => _exmpState();
}
class _exmpState extends State<exmp> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("example"),
),
body: Column(
children: <Widget>[
Center(
child: RaisedButton(onPressed: () {
Navigator.of(context).pushAndRemoveUntil(
MaterialPageRoute(
builder: (context) => my_example(),
),
(route) => false);
}),
)
],
),
);
}
}
And this is my second page my_example
class my_example extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(primarySwatch: Colors.amber),
home: my_examp(),
);
}
}
class my_examp extends StatefulWidget {
#override
_my_exampState createState() => _my_exampState();
}
class _my_exampState extends State<my_examp> {
Future<bool> onbackpress() async{
return true;
}
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: onbackpress,
child: Scaffold(
appBar: AppBar(
title: Text("my_eaxmple"),
),
),
);
}
}
The problem was i am pushing another page from my main page but i forget to remove first page for that i used the Navigator.of(context).pushAndRemoveUntil( MaterialPageRoute(builder: (context) => my_example()(route) => false); to remove the main page before navigate to another page

I was struggling with this problem, none of answers helped but finally I found the correct answer in BackButton widget source code.
When we use WillPopScope on top of our widget, we should use maybePop instead of pop method that forces the Navigator to pop the last pushed page in order to let the WillPopScope widget decides the next action.
Navigator.maybePop(context);

This is how you should use
Future<bool> _willPopCallback() async {
// await Show dialog of exit or what you want
// then
return true; //
}
//then use in the build like
WillPopScope(child: new Scaffold(), onWillPop: _willPopCallback)

I resolved this error as in my case I have a parent screen and in that, I have PageView. I was trying to call WillPopScope in one of my PageView and then I realized my parent have WillPopScope too.
That is why it is not calling WillPopScope of PageView

don't use on Scaffold(), wrap your MaterialApp as in the example
bool allowed = false;
return WillPopScope(
onWillPop: () async {
print('MJD POP TRYING TO GET BACK from login Page');
return Future.value(allowed);
},
child: MaterialApp(
title: 'Your App Title',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyLoginPage(title: 'Login Page'),
),
);

Related

save string and associated icon with shared prefs

I'm currently using the shared preferences to save a string list. Every time the page is opened, for every string entry from the list I create a list tile inside a list view. But now I don't want to only save the string, I even want to save an icon with it. But I have absolutely no idea on how to solve this
Here is my current code:
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:trainings_app/widgets/alertbox_widget.dart';
import 'package:trainings_app/widgets/team_widget.dart';
class TeamScreen extends StatefulWidget {
#override
_TeamScreenState createState() => _TeamScreenState();
}
class _TeamScreenState extends State<TeamScreen> {
late SharedPreferences sharedPreferences;
List<String> teams = [];
IconData? currentIcon;
#override
void initState() {
tryFetchData();
super.initState();
}
void tryFetchData() async {
sharedPreferences = await SharedPreferences.getInstance();
if (!sharedPreferences.containsKey('teams')) {
sharedPreferences.setStringList('teams', []);
return;
}
teams = sharedPreferences.getStringList('teams') as List<String>;
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: ListView.builder(
itemCount: teams.length,
itemBuilder: (context, index) {
return Team(
teams[index],
Icon(currentIcon),
() => removeTeam(teams[index]),
);
},
),
floatingActionButton: FloatingActionButton(
onPressed: () {
newTeam();
},
child: Icon(
CupertinoIcons.add,
),
),
);
}
void newTeam() {
showDialog<Alertbox>(
context: context,
builder: (BuildContext context) {
return Alertbox('Namen auswählen:', addTeam);
},
);
}
void addTeam(String name, IconData? icon) {
if (name.isNotEmpty) {
setState(() {
currentIcon = icon;
teams.add(name);
});
}
Navigator.pop(context);
sharedPreferences.setStringList('teams', teams);
}
void removeTeam(String name) {
setState(() {
teams.remove(name);
});
sharedPreferences.setStringList('teams', teams);
}
}
class Team extends StatelessWidget {
final String name;
final Icon icon;
final Function remove;
const Team(this.name, this.icon, this.remove);
#override
Widget build(BuildContext context) {
return Container(
padding: EdgeInsets.symmetric(horizontal: 22),
child: ListTile(
leading: Icon(icon.icon),
contentPadding: EdgeInsets.symmetric(vertical: 8.0),
title: Text(
name,
style: TextStyle(
fontSize: 18.0,
fontWeight: FontWeight.w600,
),
),
trailing: IconButton(
icon: Icon(CupertinoIcons.delete),
onPressed: () => remove(),
),
onTap: () {
Navigator.push(context,
MaterialPageRoute(builder: (context) => TeamWidget(name, icon)));
},
),
);
}
}
you can use each Icon specific id instead of IconData and store it as a List of Json:
Json.encode({title:"test", icon:61668}
and then save it in sharedPref. after that you can recall it as follows:
Icon(IconData(**YOUR SELECTED ID**, fontFamily: 'MaterialIcons'));
check the id of each icon here: link
The other solution can be using images instead of icons! or using this site to convert image to font icon and use it as follows:
Icon(IconData(int.parse('0x${e90a}',
fontFamily: 'family name given in the link above'));

Flutter re-login it does not directs to the intended home page

Flutter Logout directs to login page but after re-login it does not redirects to the intended home page.
I have used the below navigation for login
Navigator.of(context).pushReplacement(PageRouteBuilder(pageBuilder: (_, __, ___) => Home()));
My app is consist of three bottom navigation bar.Home Page is in second navigation bar. I have to logout from third navigation bar.
I have used the below code for logout
Navigator.pushNamedAndRemoveUntil(context, '/Login', (_) => false);
Also i have tried the codes too
Navigator.popAndPushNamed(context, "/Login");
Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(builder: (BuildContext context) => Login(),), (Route route) => false);
Please help me to find a solution.
This is my splash screen
class SplashState extends State<SplashScreen>{
bool isLogged = false;
startTime(){
return new Timer(Duration(milliseconds: 3000), navigateUser);
}
#override
void initState() {
super.initState();
getStoredValue();
}
void getStoredValue() async{
SharedPreferences prefs = await SharedPreferences.getInstance();
if (!prefs.containsKey('isLoggin')) {
prefs.setBool('isLoggin', false);
print("login set to False");
}
isLogged = prefs.getBool('isLoggin');
print("Status in splash -----------$isLogged");
startTime();
}
#override
Widget build(BuildContext context) {
SystemChrome.setEnabledSystemUIOverlays([]);
return Container(
height: double.infinity,
width: double.infinity,
decoration: BoxDecoration(
gradient:LinearGradient(
begin: Alignment.topLeft,
end: Alignment.bottomRight,
colors: <Color>[
colorStyle.splashPink,
colorStyle.splashOrange,
],
)
),
child: Center(
child: Image.asset("assets/images/splash_logo.png", height: 85.0),
),
);
}
void navigateUser() {
if (isLogged == true) {
Navigator.of(context).pushReplacement(
PageRouteBuilder(pageBuilder: (_, __, ___) => Home()));
}
else {
Navigator.of(context).pushReplacement(
PageRouteBuilder(pageBuilder: (_, __, ___) => Login()));
}
}
}
Logout
void logoutUser()async{
LogoutUser objLog = await createPost(logoutUrl,body);
if(objLog.statusCode == 10000){
print(("response is $resp"));
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setBool('isLoggin', false);
Navigator.pushReplacement(context, MaterialPageRoute(builder: (context) => Login()));
}
else showToast(objLog.message, duration: Toast.LENGTH_LONG);
}
Try to use shared preference to store as login key and check if it is true then go to main screen or else redirect to login screen.
First of all add shared preference dependency in your pubspec.yaml
dependencies:
flutter:
sdk: flutter
shared_preferences: ^0.5.6+2
SplashScreen.dart
This is first screen where we are check that if isLogin is true then go to HomeScreen or else redirect to LoginScreen
_autoLogin() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
if (!prefs.containsKey('isLogin')) {
prefs.setBool('isLogin', false);
}
if (prefs.getBool('isLogin')) {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => HomeScreen(),
));
} else {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => LoginScreen(),
));;
}
}
LoginScreen.dart
_setIsLogin() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setBool('isLogin', true);
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => HomeScreen(),
));
}
MaterialButton(
minWidth: MediaQuery.of(context).size.width,
padding: EdgeInsets.fromLTRB(20.0, 10.0, 20.0, 10.0),
onPressed: () {
_setIsLogin();
},
child: Text("LOGIN",
textAlign: TextAlign.center,
style: style.copyWith(
color: Colors.white,
fontWeight: FontWeight.bold,
fontSize: 18.0)),
),
HomeScreen.dart
Set isLogin as false when click on Logout
_logout() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setBool('isLogin', false);
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => LoginScreen(),
));
}
I hope this can help you!

Hello does someone successfully added Bluetooth CPCL on your Flutter project?

I tried to print in a ZEBRA ez320 Bluetooth printer I found out that it only works using cpcl code, the good news is I have the sample code for cpcl but I don't know how to integrate it on my Flutter project.
Can someone help me out?
This github https://github.com/devinim/flutter-zsdk has Zebra SDK Kit Flutter Integration
code snippet
devices = await FlutterZsdk.discoverBluetoothDevices();
devices.forEach((d) {
print('Device: ${d.friendlyName} [${d.mac}]');
});
...
d.sendZplOverBluetooth(FLUTTER_LOGO_ZPL),
full example code https://github.com/devinim/flutter-zsdk/blob/master/example/lib/main.dart
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter_zsdk/flutter_zsdk.dart';
void main() => runApp(MyApp());
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
static const String FLUTTER_LOGO_ZPL = "^XA^CI28^PON^PW560^MNN^LL460^LH0,0^LT60" +
"^GFA,6150,6150,25,,gP01XFCgP03XF8gP07XF,gP0XFE,gO01XFC,gO03XF8,gO07XF,gO0XFE,gN01XFC,gN03XF8,gN0YF,gN0XFE,gM01XFC,gM03XF8,gM0YF,gL01XFE"
",gL01XFC,gL07XF8,gL0YF,gK01XFE,gK03XFC,gK07XF8,gK0YF,gJ01XFE,gJ03XFC,gJ07XF8,gJ0YF,gI01XFE,gI03XFC,gI07XF8,gI0YF,gH01XFE,gH03XFC,gH07XF8"
",gH0YF,gG01XFE,gG03XFC,gG07XF8,gG0YF,g01XFE,g03XFC,g07XF8,g0YF,Y01XFE,Y03XFC,Y07XF8,Y0YF,X01XFE,X03XFC,X07XF8,X0YF,W01XFE,W03XFC,W07XF8"
",W0YF,V01XFE,V03XFC,V07XF8,V0YF,U01XFE,U03XFC,U07XF8,U0YF,T01XFE,T03XFC,T07XF8,T0YF,S01XFE,S03XFC,S07XF8,S0YF,R01XFE,R03XFC,R07XF8"
",R0YF,Q01XFE,Q03XFC,Q07XF8,Q0YF,P01XFE,P03XFC,P07XF8,P0YF,O01XFE,O03XFC,O07XF8,O0YF,N01XFE,N03XFC,N07XF8,N0YF,M01XFE,M03XFC,M07XF8"
",M0YF,L01XFE,L03XFC,L07XF8,L0YF,K01XFE,K03XFC,K07XF8,K0YF,J01XFE,J03XFC,J07XF8,J0YF,I01XFE,I03XFC,I07XF8,I0XFE,001XFE,003XFCN03XF"
",007XF8N07XF,00XFEO0XFE,01XFCN01XFC,03XFCN03XF8,07XF8N07XF,0XFEO0XFE,1XFCN01XFC,3XF8N03XF8,7XF8N07XF,3WFEO0XFE,1WFCN01XFC,0WF8N03XF8"
",07VFO07XF,03UFEO0XFE,01UFCN01XFC,00UF8N03XF8,007TFO07XF,003SFEO0XFE,001SFCN01XFC,I0SF8N03XF8,I07RFO07XF,I03QFEO0XFE,I01QFCN01XFC,J0QF8N03XF8"
",J07PFO07XF,J03OFEO0XFE,J01OFCN01XFC,K0OF8N03XF8,K07NFO07XF,K03MFEO0XFE,K01MFCN01XFC,L0MF8N03XF8,L07LFO07XF,L03KFEO0XFE,L01KFCN01XFC,M0KF8N03XF8"
",M07JFO07XF,M03IFEO0XFE,M01IFCN01XFC,N0IF8N03XF8,N07FFO07XF,N03FEO0XFE,N01FCN01XFC,O0F8N03XF8,O07O07XF,O02O0XFE,X01XFC,X03XF8,X07XF,X0XFE,W01XFC"
",W03XF8,W07XF,W0XFE,V01XFC,V03XF8,V07XF,V0XFE,U01XFC,U03XF8,U07XF,U0XFE,T01XFC,T07XF8,T07XF,T03XF8,T01XFC,U0XFE,U07XF,U03XF8,U01XFC,V0XFE,V07XF"
",V03XF8,V01XFC,W0XFE,W07XF,W07XF8,W03XFC,X0XFE,X07XF,X07XF8,X03XFC,X01XFE,Y07XF,Y07XF8,Y03XFC,Y01XFE,g0YF,g07XF8,g03XFC,g01XFE,gG0YF,gG07XF8,gG03XFC"
",gG01XFE,gH0YF,gH07XF8,gH03XFC,gH01XFE,gI0YF,gI07XF8,gI03XFC,gI01XFC,gJ0XFE,gJ07XF,gJ03XF8,gJ01XFC,gK0XFE,gK07XF,gK03XF8,gK01XFC,gL0XFE,gL07XF,gL03XF8"
",gL01XFC,gM0XFE,gM07XF,gM03XF8,gM01XFC,gN0XFE,gN07XF,gN03XF8,gN01XFC,gO0XFE,gO07XF,gO03XF8,gO01XFC,gP0XFE,gP07XF,gR01VF8"
",^FS ^XZ";
List<ZebraBluetoothDevice> _devices = List();
#override
void initState() {
super.initState();
__init();
}
// Platform messages are asynchronous, so we initialize in an async method.
Future<void> __init() async {
List<ZebraBluetoothDevice> devices = List();
try {
devices = await FlutterZsdk.discoverBluetoothDevices();
devices.forEach((d) {
print('Device: ${d.friendlyName} [${d.mac}]');
});
} catch (e) {
showDialog(context: context, child: Text(e));
//throw e;
print('Error' + e);
}
if (!mounted) return;
setState(() {
_devices = devices;
});
}
String levelText = "Querying...";
_level(ZebraBluetoothDevice d) {
d.batteryLevel().then((t) {
setState(() {
levelText = t;
});
});
}
Widget _listPrinters() {
List<Widget> items = List();
if (_devices.length < 1) {
items.add(ListTile(
title: Text("Not found any or still searching"),
));
} else {
items.addAll([
ListTile(
title: Text("Found ${_devices.length} device(s)"),
),
SizedBox(height: 50),
]);
_devices.forEach((d) {
_level(d);
items.add(
ListTile(
title: Text(d.friendlyName),
subtitle: Text(d.mac + "[%${levelText}]"),
leading: IconButton(icon: Icon(Icons.list), onPressed: () => d.properties()),
trailing: IconButton(
icon: Icon(Icons.print),
onPressed: () => d.sendZplOverBluetooth(FLUTTER_LOGO_ZPL),
),
),
);
});
}
return ListView(
padding: EdgeInsets.all(24),
children: items,
);
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: const Text('Zebra Plugin Example App'),
),
body: _listPrinters(),
),
);
}
}

Go to respective screen when FlatButton is pressed from AutoCompleteTextField

With autocomplete_textfield package of Flutter, I have made a search bar. When it returns the result as a container, I want to a button in it that'll push to the respected screen of the search result.
But how can I make the button dynamic so that it can go to the screen based on the search result?
For example, if the search result is Aishim, how can I get the button to go to AishimWidget() when pressed?
I have added the FlatButton to the result container. That goes to AishimWidget when pressed.
import 'package:autocomplete_textfield/autocomplete_textfield.dart';
import 'package:flutter/material.dart';
import 'package:smartdoctor/screens/aishim_widget.dart';
class SearchWidget extends StatefulWidget {
#override
State < StatefulWidget > createState() => _SearchWidgetState();
}
class _SearchWidgetState extends State < SearchWidget > {
#override
Widget build(BuildContext context) {
return new Scaffold(
body: SecondPage(),
);
}
}
class ArbitrarySuggestionType {
String name;
ArbitrarySuggestionType(this.name);
}
class SecondPage extends StatefulWidget {
#override
State < StatefulWidget > createState() => _SecondPageState();
}
class _SecondPageState extends State < SecondPage > {
List < ArbitrarySuggestionType > suggestions = [
new ArbitrarySuggestionType("Minamishima"),
new ArbitrarySuggestionType("Aishim"),
];
GlobalKey key =
new GlobalKey < AutoCompleteTextFieldState < ArbitrarySuggestionType >> ();
AutoCompleteTextField < ArbitrarySuggestionType > textField;
ArbitrarySuggestionType selected;
_SecondPageState() {
textField = new AutoCompleteTextField < ArbitrarySuggestionType > (
decoration: new InputDecoration(
hintText: "Search:", suffixIcon: new Icon(Icons.search)),
itemSubmitted: (item) => setState(() => selected = item),
key: key,
suggestions: suggestions,
itemBuilder: (context, suggestion) => new Padding(
child: new ListTile(
title: new Text(suggestion.name)),
padding: EdgeInsets.all(8.0)),
itemSorter: (a, b) => a.stars == b.stars ? 0 : a.stars > b.stars ? -1 : 1,
itemFilter: (suggestion, input) =>
suggestion.name.toLowerCase().startsWith(input.toLowerCase()),
);
}
#override
Widget build(BuildContext context) {
return new Scaffold(
body: new Column(children: [
new Padding(
padding: EdgeInsets.fromLTRB(0.0, 64.0, 0.0, 0.0),
child: new Card(
child: selected != null ?
new Column(children: [
new Container(
child: FlatButton(
onPressed: () => this.onButtonPressed(context))),
new ListTile(
title: new Text(selected.name)),
]) :
new Icon(Icons.home))),
]),
);
}
void onButtonPressed(BuildContext context) => Navigator.push(context, MaterialPageRoute(builder: (context) => AishimWidget()));
}
But it's not dynamic. Can I use any if statement for deciding which screen to go to? Or is there any better way of doing this?
You can use named-routes https://flutter.dev/docs/cookbook/navigation/named-routes
Map each page with a string
In onButtonPressed, use string
Navigator.pushNamed(context, '/second');
or in your case might looks like the following, you can pass any string you want like selected.name or suggestion.name
Navigator.pushNamed(context, suggestion.name);
define your route, map each page with a string
void main() {
runApp(MaterialApp(
title: 'Named Routes Demo',
// Start the app with the "/" named route. In this case, the app starts
// on the FirstScreen widget.
initialRoute: '/',
routes: {
// When navigating to the "/" route, build the FirstScreen widget.
'/': (context) => FirstScreen(),
// When navigating to the "/second" route, build the SecondScreen widget.
'/second': (context) => SecondScreen(),
},
));
}
full example code
import 'package:flutter/material.dart';
//void main() => runApp(MyApp());
void main() {
runApp(MaterialApp(
title: 'Named Routes Demo',
// Start the app with the "/" named route. In this case, the app starts
// on the FirstScreen widget.
initialRoute: '/',
routes: {
// When navigating to the "/" route, build the FirstScreen widget.
'/': (context) => FirstScreen(),
// When navigating to the "/second" route, build the SecondScreen widget.
'/second': (context) => SecondScreen(),
},
));
}
class FirstScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('First Screen'),
),
body: Center(
child: RaisedButton(
child: Text('Launch screen'),
onPressed: () {
// Navigate to the second screen using a named route.
Navigator.pushNamed(context, '/second');
},
),
),
);
}
}
class SecondScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Second Screen"),
),
body: Center(
child: RaisedButton(
onPressed: () {
// Navigate back to the first screen by popping the current route
// off the stack.
Navigator.pop(context);
},
child: Text('Go back!'),
),
),
);
}
}

Is there a way to send a request after the user has stopped typing?

I am looking for a way to send an API request after the user has stopped typing for X amount of seconds.
The way I am sending the request is through the onTextChanged callback, however, that sends a request on every key press
I have seen ways to do this with a timeout in React, however, I am relatively new to flutter so any help would be appreciated
you can use the below code to do this:
import 'package:flutter/material.dart';
import 'dart:async';
class Test extends StatefulWidget {
#override
State<StatefulWidget> createState() {
return _TestState();
}
}
class _TestState extends State<StatefulWidget> {
Timer searchOnStoppedTyping;
_onChangeHandler(value ) {
const duration = Duration(milliseconds:800); // set the duration that you want call search() after that.
if (searchOnStoppedTyping != null) {
setState(() => searchOnStoppedTyping.cancel()); // clear timer
}
setState(() => searchOnStoppedTyping = new Timer(duration, () => search(value)));
}
search(value) {
print('hello world from search . the value is $value');
}
#override
Widget build(BuildContext context) {
return TextField(
onChanged: _onChangeHandler,
decoration: InputDecoration(
hintText: 'Search ....'
),
);
}
}
The usual way to do this in Flutter is using RxDart and its debounce() method. It allows to wait a small period before launching a specific call.
In the following full example you see it in action with a time of 1 second. In the example, a message is shown where the call to the server should be dispatched.
import 'package:flutter/material.dart';
import 'package:rxdart/rxdart.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final subject = new PublishSubject<String>();
bool isLoading = false;
GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey();
void _textChanged(String text) {
if (text.isEmpty) {
setState(() {
isLoading = false;
});
return;
}
setState(() {
isLoading = true;
});
scaffoldKey.currentState.showSnackBar(new SnackBar(
content: new Text("Search for ${text}"),
));
}
#override
void initState() {
super.initState();
subject.stream.debounce(new Duration(milliseconds: 1000)).listen(_textChanged);
}
#override
void dispose() {
subject.close();
super.dispose();
}
#override
Widget build(BuildContext context) {
return new Scaffold(
key: scaffoldKey,
appBar: new AppBar(
title: new Text("Debounce demo"),
),
body: new Container(
padding: new EdgeInsets.all(8.0),
child: new Column(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
new TextField(
decoration: new InputDecoration(
hintText: 'Type text to search',
),
onChanged: (string) => (subject.add(string)),
),
isLoading
? Padding(
padding: const EdgeInsets.all(20.0),
child: new CircularProgressIndicator(),
)
: new Container(),
],
),
),
);
}
}
You can see this code in action in the following article and code by Norbert Kozsir

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