problem automatic log off when I navigate between tabs (Firebase Auth rest API) - flutter

Question

Hi I'm building an app and I'm using authentication using Firebase Auth rest API but the problem is that when I navigate between my tabs my app logOut automatically I don't know if it's expiration of token problem or something else so can some one help with that?
this is my auth part it's in my provider package
class Auth with ChangeNotifier {
String _token;
String _userId;
bool get isAuth {
return token != null;
}
String get token{
return _token;
}
String get userId {
return _userId;
}
Future<void> signup(String email, String password) async {
final url = Uri.parse(
'https://...myurl...'
);
try {
final response = await http.post(url,body: json.encode(
{
'email': email,
'password':password,
'returnSecureToken': true,
},), );
final responseData = json.decode(response.body);
if(responseData['error'] != null){
throw Exception();
}
_token = responseData['idToken'];
_userId = responseData['localId'];
notifyListeners();
} catch (error) {
throw error;
} }
Future<void> login(String email, String password) async {
final url = Uri.parse( 'https://...myurl...' );
try {
final response = await http.post(
url,
body: json.encode(
{
'email': email,
'password':password,
'returnSecureToken': true,
},),);
} catch (error) {
throw error;
} }}
this is the Ath screen:
enum AuthMode { Signup, Login }
class AuthScreen extends StatelessWidget {
static const routeName = '/auth';
#override
Widget build(BuildContext context) {
final deviceSize = MediaQuery.of(context).size;
bool _isLoading= false;
return Scaffold(
backgroundColor: Colors.pinkAccent[100],
body: SizedBox(
height: double.infinity,
child: Stack(
children: <Widget>[
Container(
padding: EdgeInsets.all(8),
margin: EdgeInsets.all(8),
child: Expanded(
child:
SizedBox(
height: 280,
),
),
),
SingleChildScrollView(
child: Container(
height: deviceSize.height,
width: deviceSize.width,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
SizedBox(
height: 60,
child: LogoBekery(
color1:Colors.white,
color2:Colors.white,
color3:Colors.white,
),
),
SizedBox(
child: ImageSlideshow(
isLoop: true,
width: double.infinity,
height: 250,
initialPage: 0,
indicatorColor: Colors.pink,
indicatorBackgroundColor: Colors.grey,
children: [
Image.asset(
'assets/images/logoA.png',
fit: BoxFit.fill,
),
Image.asset(
'assets/images/logoB.png',
fit: BoxFit.fill,
),
Image.asset(
'assets/images/logoC.png',
fit: BoxFit.fill,
),
Image.asset(
'assets/images/logoD.png',
fit: BoxFit.fill,
),
],
onPageChanged: (value) {
// print('Page changed: $value');
},
autoPlayInterval: 3000,
),
),
Flexible(
flex: deviceSize.width > 600 ? 2 : 1,
child: AuthCard(),
),
],
),
),
),
],
),
),
);
}
void _submitAuthForm(
String email,
String password,
String username,
bool isLogin,
BuildContext ctx,
)
async {
UserCredential authResult; }
}
class AuthCard extends StatefulWidget {
const AuthCard({
Key key,
}) : super(key: key);
#override
_AuthCardState createState() => _AuthCardState();
}
class _AuthCardState extends State<AuthCard> {
final GlobalKey<FormState> _formKey = GlobalKey();
AuthMode _authMode = AuthMode.Login;
Map<String, String> _authData = {
'email': '',
'password': '',
};
var _isLoading = false;
final _passwordController = TextEditingController();
Future<void> _submit() async{
if (!_formKey.currentState.validate()) {
// Invalid!
return;
}
_formKey.currentState.save();
setState(() {
_isLoading = true;
});
try {
if (_authMode == AuthMode.Login) {
await Provider.of<Auth>(context, listen: false).login(
_authData['email'] ,
_authData['password'] );
} else {
await Provider.of<Auth>(context, listen: false).signup(
_authData['email'] ,
_authData['password'] );
}
Navigator.of(context).pushReplacementNamed(ProductOverviewScreen.routeName);
} on Exception catch (error) {
var errorMsg = 'Authentification Failed!';
}catch (error){
var errorMsg = 'Could not authentificate! please try later...';
}
setState(() {
_isLoading = false;
});
}
void _switchAuthMode() {
if (_authMode == AuthMode.Login) {
setState(() {
_authMode = AuthMode.Signup;
});
} else {
setState(() {
_authMode = AuthMode.Login;
});
}
}
#override
Widget build(BuildContext context) {
final deviceSize = MediaQuery.of(context).size;
return Card(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10.0),
),
elevation: 8.0,
child: Container(
height: _authMode == AuthMode.Signup ? 320 : 260,
constraints:
BoxConstraints(minHeight: _authMode == AuthMode.Signup ? 150 : 260),
width: deviceSize.width * 0.8,
padding: EdgeInsets.all(16.0),
child: Form(
key: _formKey,
child: SingleChildScrollView(
child: Column(
children: <Widget>[
TextFormField(
decoration: InputDecoration(labelText: 'E-Mail'),
keyboardType: TextInputType.emailAddress,
validator: (value) {
if (!RegExp(r'\S+#\S+\.\S+').hasMatch(value)) {
return 'Invalid email!';
}
return null;
return null;
},
onSaved: (value) {
_authData['email'] = value;
},
),
TextFormField(
decoration: InputDecoration(labelText: 'Password'),
obscureText: true,
controller: _passwordController,
validator: (value) {
if (value.isEmpty || value.length < 5) {
return 'Password is too short!';
}
},
onSaved: (value) {
_authData['password'] = value;
},
),
if (_authMode == AuthMode.Signup)
TextFormField(
enabled: _authMode == AuthMode.Signup,
decoration: InputDecoration(labelText: 'Confirm Password'),
obscureText: true,
validator: _authMode == AuthMode.Signup
? (value) {
if (value != _passwordController.text) {
return 'Passwords do not match!';
}
}
: null,
),
SizedBox(
height: 20,
),
if (_isLoading)
CircularProgressIndicator()
else
RaisedButton(
child:
Text(_authMode == AuthMode.Login ? 'LOGIN' : 'SIGN UP'),
onPressed: _submit,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(30),
),
padding:
EdgeInsets.symmetric(horizontal: 30.0, vertical: 8.0),
color: Theme.of(context).primaryColor,
textColor: Theme.of(context).primaryTextTheme.button.color,
),
FlatButton(
child: Text(
'${_authMode == AuthMode.Login ? 'SIGNUP' : 'LOGIN'}'),
onPressed: _switchAuthMode,
padding: EdgeInsets.symmetric(horizontal: 30.0, vertical: 4),
materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
textColor: Theme.of(context).primaryColor,
),
],
),
),
),
),
);
}
}

Answer 1

Your _token and _userId is only set after registering. You don't set it after loging in. Therefore token could be null and isAuth will return false.
I think you should set the value of _token and _userId after the login function.
Future<void> login(String email, String password) async {
final url = Uri.parse('https://...myurl...');
try {
final response = await http.post(
url,
body: json.encode(
{
'email': email,
'password': password,
'returnSecureToken': true,
},
),
);
// added from here
final responseData = json.decode(response.body);
if (responseData['error'] != null) {
throw Exception();
}
_token = responseData['idToken'];
_userId = responseData['localId'];
// to here.
} catch (error) {
throw error;
}
}