trying to get saved data by sharedpreferences
while I am practicing flutter sharedpreferences is not saving anything(posting my code below)
firstly created one textfield, button and one textwidget to show what I typed in textfield when I click button
I think everything ok there is not showing any error but when I click button text widget will show what I typed but that not saving to get after the app closed(code below)
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
main() {
WidgetsFlutterBinding.ensureInitialized();
runApp(MyApp());
}
class MyApp extends StatefulWidget {
// const MyApp({ Key? key }) : super(key: key);
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
String text = "";
#override
void initState() {
super.initState();
getStringValuesSF();
}
final _controller = TextEditingController();
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
text,
style: TextStyle(fontWeight: FontWeight.bold, fontSize: 40),
),
ElevatedButton(
onPressed: () async {
setState(() {
text = _controller.text;
});
SharedPreferences prefs =
await SharedPreferences.getInstance();
prefs.setString('stringValue', text);
},
child: Text("Show bigger")),
TextField(
controller: _controller,
),
],
),
),
),
);
}
//method to get the string
getStringValuesSF() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
//Return String
String stringValue = prefs.getString('stringValue');
this.text = stringValue;
}
}
you just have to change below method,
getStringValuesSF() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
//Return String
String stringValue = prefs.getString('stringValue');
_controller.text = stringValue; //change !!!
}
use setState to see changes after fetching data:-
getStringValuesSF() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
//Return String
String stringValue = prefs.getString('stringValue');
setState((){this.text = stringValue;});
}
Related
I'm try to learn how to get token. What is wrong with the code I wrote?
I'm try to learn how to get token.
import 'package:shared_preferences/shared_preferences.dart';
import '../common/constant.dart';
Use this sample:
class UtilSharedPreferences {
static Future<String> getToken() async {
var prefs = await SharedPreferences.getInstance();
return prefs.getString('Token') ?? '';
}
static Future<bool> setToken(String value) async {
var prefs = await SharedPreferences.getInstance();
return prefs.setString('Token', value);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({
Key? key,
}) : super(key: key);
#override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String str = '';
gettoken() async {
str = await UtilSharedPreferences.getToken();
setState(() {});
}
#override
void initState() {
// TODO: implement initState
super.initState();
gettoken();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Text('Token :$str'),
Center(
child: InkWell(
onTap: () {
var result = UtilSharedPreferences.setToken('hi');
if(result){
print('success');
}
},
child: Text('save token'),
),
),
],
),
);
}
}
Future is asynchronous and you must use await to get the desired value.
user = await UtilSharedPreferencs();
The async keyword is required to use async. So implement it separately as a method
void setUser() async {
user = await UtilSharedPreferencs();
}
void initState(){
super.initState();
setUser();
}
I am learning how to use the SharedPreferences library in Flutter.
I created this code and I would like the counter and counter2 variables once I close and reopen the app to remain as the last save.
However, when I reopen the app the counter and counter2 values return to 0.
Can anyone explain to me where I am going wrong?
Thank you.
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'data.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int counter = 0;
int counter2 = 0;
increment() {
setState(() {
counter += 1;
counter2 += 2;
});
}
loadData() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
setState(() {
String? json = prefs.getString('UserData');
print('loaded json: $json');
if (json == null) {
print('NO DATA (null)');
} else {
Map<String, dynamic> map = jsonDecode(json);
print('map $map');
final data = Data.fromJson(map);
print('Data ${data.counter}, ${data.counter2}');
}
});
}
saveData() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
final _data = Data(counter: counter, counter2: counter2);
String json = jsonEncode(_data);
print('saved json: $json');
prefs.setString('UserData', json);
}
clearData() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.clear();
print('data cleared');
}
/// dichiarare l' initState()
#override
void initState() {
super.initState();
loadData();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
const Text(
'You have pushed the button this many times:',
),
Text(
'c: $counter, c2: $counter2',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
increment();
saveData();
},
tooltip: 'Increment',
child: const Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class Data {
int counter = 0;
int counter2 = 0;
Data({required this.counter, required this.counter2});
Map<String, dynamic> toJson() {
return {
'counter': counter,
'counter2': counter2,
};
}
Data.fromJson(Map<String, dynamic> json) {
counter = json['counter'];
counter2 = json['counter2'];
}
}
I agree with the other answer, the best is to use a FutureBuilder. But you can make your current code work with simply adding two lines at the end of loadData:
loadData() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
setState(() {
String? json = prefs.getString('UserData');
print('loaded json: $json');
if (json == null) {
print('NO DATA (null)');
} else {
Map<String, dynamic> map = jsonDecode(json);
print('map $map');
final data = Data.fromJson(map);
print('Data ${data.counter}, ${data.counter2}');
// add these lines
counter = data.counter;
counter2 = data.counter2;
}
});
}
What happens (as the other answer says) is that your widget is first built without knowing the values from SharedPreferences. After a little time this first build is done, the loadData future completes, and with setState the widget is rebuilt.
In a real application you'd like to avoid unnecessary builds, so you'd rather display a progress indicator while async data is being loaded, check FutureBuilder.
A short answer is that when you call loadData(); inside initState the function is performed asynchronously relative to the rest of the widget, so your Scaffold is built before the data is available. This is why you are seeing the data in from your print but not in the app.
One way to address it is to us a https://api.flutter.dev/flutter/widgets/FutureBuilder-class.html
I am trying to apply conditions on widget when user is logged in, display widget logout else display login button.How is it possible?
Before login
After Login
I used shred_preferences package saving, getting and removing used data.
Here my codes:
shared_preferences
import 'package:shared_preferences/shared_preferences.dart';
class PrefServices{
Future createCache(String username, String password) async {
SharedPreferences _preferences = await SharedPreferences.getInstance();
_preferences.setString("username", username);
_preferences.setString("password", password);
}
Future readCache(String username) async {
SharedPreferences _preferences = await SharedPreferences.getInstance();
var username = _preferences.getString("username")?? "null";
// _preferences.getString("password");
return username;
}
Future<void> removeCache(String username, String password) async {
SharedPreferences _preferences = await SharedPreferences.getInstance();
_preferences.remove("username");
_preferences.remove("password");
}
}
Profile Screen
import 'dart:async';
import 'package:clothing_roll/shred_preferences/shred_preferences_services.dart';
import 'package:clothing_roll/ui/widget/profile/login_widget.dart';
import 'package:clothing_roll/ui/widget/profile/profiles_widget.dart';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
class ProfileScreen extends StatefulWidget {
const ProfileScreen({ Key? key }) : super(key: key);
#override
_ProfileScreen createState() => _ProfileScreen();
}
class _ProfileScreen extends State<ProfileScreen> {
final PrefServices _prefServices = PrefServices();
#override
void initState() {
_prefServices.readCache("username").then((value) {
print(value.toString());
if (value != null) {
return Timer(Duration(seconds: 1),
() => ProfileWidget());
} else {
return Timer(Duration(seconds: 1),
() => LoginWidget());
}
});
super.initState();
}
#override
Widget build(BuildContext context) {
return Container();
}
}
Note: I have used Getx package
create a bool variable for conmdition check
add ternary operator to bool variable and change the conditions
class Test1 extends StatelessWidget {
Controller controller = Get.put(Controller());
Test1({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Container(
width: Get.width,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
ElevatedButton(
onPressed: () {
controller.isLogged.value = !controller.isLogged.value;
},
child: Text("Press to change value")),
Obx(
() => controller.isLogged.value
? ElevatedButton(onPressed: () {}, child: Text("logged In"))
: ElevatedButton(onPressed: () {}, child: Text("Logged Out")),
),
],
),
),
);
}
}
I know that there are other ways of achieving this, but I want to use a Future via initState() to obtain a List using SharedPreferences without using await. The following illustrates what I want to achieve, and it does work. Because I have never used this pattern previously, I'm just unsure if it's the best way (without using await). Is there a better way without using await?
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
class _MyHomePageState extends State<MyHomePage> {
SharedPreferences _prefs;
String _sMessage1;
String _sMessage2;
List<String> _lsCategories;
#override
void initState() {
super.initState();
Future<void> future = _initPreferences();
future.then((_) {
if (_prefs != null) {
try {
_lsCategories = _prefs.getStringList("categories") ?? [];
debugPrint("Categories = $_lsCategories");
_sMessage2 = "Categories loaded OK";
} catch (vError) {
_sMessage2 = ("Error loading categories = $vError");
}
}
setState(() {});
});
}
Future<void> _initPreferences() {
return SharedPreferences.getInstance().then((prefs) {
_prefs = prefs;
_sMessage1 = "Preferences initialized OK";
}).catchError((vError) {
_sMessage1 = "Error initializing preferences = ${vError.toString()}";
_sMessage2 = "Unable to load categories";
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
_createText(_sMessage1),
SizedBox(height: 20),
_createText(_sMessage2),
],
),
),
);
}
}
Text _createText(String sText) {
return Text(sText == null ? "" : sText,
style: TextStyle(
color: Colors.red[500], fontWeight: FontWeight.bold, fontSize: 20));
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Future Test',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: "Flutter Future Test"),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
What you did is fine in terms of asynchrony. However, it's too verbose. For example, you do not need to transfer the prefs instance through state.
Another improvement could be to check whether the widget is still mounted when the Future is done. (If you use a FutureBuilder, you don't need to worry about this.)
A problem with your code is that you're setting state variables outside setState(). It is not guaranteed to work well that way, I swear I had old state used sometimes when I did that. You should set them within setState()
Here are a couple of different ways I would prefer to code it:
#override
void initState() {
super.initState();
SharedPreferences.getInstance().then((prefs) {
if(!mounted) return;
setState(() {
_prefs = prefs;
_lsCategories = _prefs.getStringList("categories") ?? [];
debugPrint("Categories = $_lsCategories");
_sMessage2 = "Categories loaded OK";
});
}).catchError((vError) {
setState(() {
_sMessage2 = ("Error loading categories = $vError");
});
});
}
#override
void initState() {
super.initState();
_initPreferences();
}
Future<void> _initPreferences() async {
final prefs = await SharedPreferences.getInstance();
if (!mounted) return;
setState(() {
try {
_prefs = prefs;
_lsCategories = _prefs.getStringList("categories") ?? [];
debugPrint("Categories = $_lsCategories");
_sMessage2 = "Categories loaded OK";
} catch (vError) {
_sMessage2 = ("Error loading categories = $vError");
}
});
}
I'm a fairly inexperienced coder.
I have a Drawer which I have created as a separate class. The issue I'm having is the dynamic data for the Drawer is not populating.
I am expecting the data being retrieved from Shared Preferences should populate the third line of my view with the value of currUserL.
It's being evaluated correctly, and returns the value of currUserL to the console, but is not updated in the Drawer.
I've loaded up a about button (triggering the update method) that works when pressed manually, but data persists only while the drawer remains open. It reverts when the drawer is closed.
drawerPatient.dart
class DrawerPatient extends StatefulWidget {
DrawerPatient({Key key}) : super(key: key);
#override
_DrawerPatientState createState() => new _DrawerPatientState();
}
class _DrawerPatientState extends State<DrawerPatient> {
String currUserL = "nv3";
Future getPref() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
currUserL = prefs.getString('currUserLast');
debugPrint('user: $currUserL');
}
#override
void initState() {
getPref();
}
void update() {
setState(() {
getPref();
});
}
#override
Widget build(BuildContext context) {
return Drawer(
child: new ListView(
children: <Widget>[
new DrawerHeader(
child: new Text('Patient Management'),
),
new ListTile(
title: new Text('search'),
onTap: () {},
),
new ListTile(
title: new Text(currUserL),
onTap: () {},
),
new Divider(),
new ListTile(
title: new Text('About'),
onTap: update,
),
],
));
}
}
userList.dart
class UserList extends StatefulWidget {
UserList({Key key, this.title}) : super(key: key);
final String title;
final String titleHead = "User List";
#override
_UserListState createState() => new _UserListState();
}
class _UserListState extends State<UserList> {
: sortStr}, headers: {"Accept": "application/json"});
setState(() {
data = json.decode(response.body);
});
}
#override
void initState() {
this.makeRequest();
// DrawerPatient().createState().update();
}
void _refresh() {
setState(() {});
}
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("Patient List"),
drawer: new DrawerPatient(key: new UniqueKey()),
...
Drawer when opened
Drawer after clicking about (update)
So I found the answer, thanks to #Dinesh for pointing me in the right direction.
The answer was to put the setState as a dependency on the async get prefs.
Future getPref() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
setState(() {
currUserI = prefs.getString('currUserId');
currUserF = prefs.getString('currUserFirst');
currUserL = prefs.getString('currUserLast');
debugPrint('user: $currUserL');
});
}
Can you try this,
Future getCurrentUser() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
return prefs.getString('currUserLast');
}
void update() {
val tempName = getCurrentUser();
setState(() {
currUserL = tempName;
});
}
Reason: Basically wait for the async method before calling setState