How do I deal with logins on different devices based on API response in flutter? - api

Question

I'm confused about how to deal with multiple logins with different devices, and I want to give the function back to the login layout when there are other devices that have just logged in to the same user
Future<EventArticleList> getEventArticleList(String token) async {
BuildContext context;
Map<String, String> headers = {
"Accept": "application/json",
"Authorization": "Bearer $token"
};
var response = await client.get('$endpoint/', headers: headers);
if (response.statusCode == 200) {
print("Masuk Data");
return EventArticleList.fromJson(
json.decode(response.body),
);
} else if (response.statusCode == 401) {
print("401");
return Navigator.of(context)
.pushNamedAndRemoveUntil(RoutePaths.Login, (_) => false);
} else {
throw Exception("ini Eror apa ?");
}
}
the compilation appears I try to add the navigator back to status.code == 401
NoSuchMethodError: The method 'ancestorStateOfType' was called on null

Answer 1

Try this code
Your main class
import 'package:flutter/material.dart';
import 'package:flutterapitut/view/adddata.dart';
import 'package:flutterapitut/view/dashboard.dart';
import 'package:flutterapitut/view/login.dart';
import 'package:flutterapitut/view/register.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
final String title='';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter CRUD API',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: LoginPage(title: 'Flutter CRUD API'),
routes: <String,WidgetBuilder>{
'/dashboard' : (BuildContext context) => new Dashboard(title:title),
'/login' : (BuildContext context) => new LoginPage(title:title),
},
);
}
}
Your Database Helper class
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'package:shared_preferences/shared_preferences.dart';
class DatabaseHelper{
String serverUrl = "http://flutterapitutorial.codeforiraq.org/api";
var status ;
var token ;
loginData(String email , String password) async{
String myUrl = "$serverUrl/login1";
final response = await http.post(myUrl,
headers: {
'Accept':'application/json'
},
body: {
"email": "$email",
"password" : "$password"
} ) ;
status = response.body.contains('error');
var data = json.decode(response.body);
if(status){
print('data : ${data["error"]}');
}else{
print('data : ${data["token"]}');
_save(data["token"]);
}
}
_save(String token) async {
final prefs = await SharedPreferences.getInstance();
final key = 'token';
final value = token;
prefs.setString(key, value);
}
read() async {
final prefs = await SharedPreferences.getInstance();
final key = 'token';
final value = prefs.get(key ) ?? 0;
print('read : $value');
}
}
Your login class
import 'package:flutter/material.dart';
import 'package:flutterapitut/Controllers/databasehelper.dart';
import 'package:flutterapitut/view/dashboard.dart';
import 'package:flutterapitut/view/register.dart';
import 'package:shared_preferences/shared_preferences.dart';
class LoginPage extends StatefulWidget{
LoginPage({Key key , this.title}) : super(key : key);
final String title;
#override
LoginPageState createState() => LoginPageState();
}
class LoginPageState extends State<LoginPage> {
read() async {
final prefs = await SharedPreferences.getInstance();
final key = 'token';
final value = prefs.get(key ) ?? 0;
if(value != '0'){
Navigator.of(context).push(
new MaterialPageRoute(
builder: (BuildContext context) => new Dashboard(),
)
);
}
}
#override
initState(){
read();
}
DatabaseHelper databaseHelper = new DatabaseHelper();
String msgStatus = '';
final TextEditingController _emailController = new TextEditingController();
final TextEditingController _passwordController = new TextEditingController();
_onPressed(){
setState(() {
if(_emailController.text.trim().toLowerCase().isNotEmpty &&
_passwordController.text.trim().isNotEmpty ){
databaseHelper.loginData(_emailController.text.trim().toLowerCase(),
_passwordController.text.trim()).whenComplete((){
if(databaseHelper.status){
_showDialog();
msgStatus = 'Check email or password';
}else{
Navigator.pushReplacementNamed(context, '/dashboard');
}
});
}
});
}
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Login',
home: Scaffold(
appBar: AppBar(
title: Text('Login'),
),
body: Container(
child: ListView(
padding: const EdgeInsets.only(top: 62,left: 12.0,right: 12.0,bottom: 12.0),
children: <Widget>[
Container(
height: 50,
child: new TextField(
controller: _emailController,
keyboardType: TextInputType.emailAddress,
decoration: InputDecoration(
labelText: 'Email',
hintText: 'Place your email',
icon: new Icon(Icons.email),
),
),
),
Container(
height: 50,
child: new TextField(
controller: _passwordController,
keyboardType: TextInputType.text,
decoration: InputDecoration(
labelText: 'Password',
hintText: 'Place your password',
icon: new Icon(Icons.vpn_key),
),
),
),
new Padding(padding: new EdgeInsets.only(top: 44.0),),
Container(
height: 50,
child: new RaisedButton(
onPressed: _onPressed,
color: Colors.blue,
child: new Text(
'Login',
style: new TextStyle(
color: Colors.white,
backgroundColor: Colors.blue),),
),
),
new Padding(padding: new EdgeInsets.only(top: 44.0),),
Container(
height: 50,
child: new Text(
'$msgStatus',
textAlign: TextAlign.center,
overflow: TextOverflow.ellipsis,
style: TextStyle(fontWeight: FontWeight.bold),
),
),
new Padding(padding: new EdgeInsets.only(top: 44.0),),
Container(
height: 50,
child: new FlatButton(
onPressed: ()=>Navigator.of(context).push(
new MaterialPageRoute(
builder: (BuildContext context) => new RegisterPage(),
)
)
,
color: Colors.blue,
child: new Text(
'Register',
style: new TextStyle(
color: Colors.white,
),),
),
),
],
),
),
),
);
}
void _showDialog(){
showDialog(
context:context ,
builder:(BuildContext context){
return AlertDialog(
title: new Text('Failed'),
content: new Text('Check your email or password'),
actions: <Widget>[
new RaisedButton(
child: new Text(
'Close',
),
onPressed: (){
Navigator.of(context).pop();
},
),
],
);
}
);
}
}
Here Dashboard is the class you expected to navigate after successfully login
Want more code visite here I hope this work correctly