ChangeNotifierProvider does not update the model - flutter

Question

i am quite new with flutter. I am trying to add a ChangeNotifierProvider into my app. I use flutter_azure_b2c to log in a user, in order to handle to login outcome I have the following code:
AzureB2C.registerCallback(B2COperationSource.POLICY_TRIGGER_INTERACTIVE,
(result) async {
if (result.reason == B2COperationState.SUCCESS) {
List<String>? subjects = await AzureB2C.getSubjects();
if (subjects != null && subjects.isNotEmpty) {
B2CAccessToken? token = await AzureB2C.getAccessToken(subjects[0]);
if (!mounted || token == null) return;
final encodedPayload = token.token.split('.')[1];
final payloadData =
utf8.fuse(base64).decode(base64.normalize(encodedPayload));
final claims = Claims.fromJson(jsonDecode(payloadData));
var m = Provider.of<LoginModel>(context);
m.logIn(claims);
}
}
});
The problem is that when it arrives to var m = Provider.of<LoginModel>(context); the execution stops with out errors without executing m.logIn(claims);, so the model is not changed and the consumer is not called.
Any idea?
This is my consumer:
class App extends StatelessWidget {
const App({super.key});
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider(
create: (context) => LoginModel(),
child: MaterialApp(
debugShowCheckedModeBanner: false,
theme: appTheme,
home: Consumer<LoginModel>(
builder: (context, value, child) =>
value.claims != null ? const Home() : const Login(),
)),
);
}
}
class LoginModel extends ChangeNotifier {
Claims? _claims;
logIn(Claims claims) {
_claims = claims;
notifyListeners();
}
logOut() {
_claims = null;
notifyListeners();
}
Claims? get claims => _claims;
}
My LoginWidget:
class Login extends StatefulWidget {
const Login({super.key});
#override
LoginState createState() => LoginState();
}
class LoginState extends State<Login> {
B2CConfiguration? _configuration;
checkLogin(BuildContext context) async {
List<String>? subjects = await AzureB2C.getSubjects();
if (subjects != null && subjects.isNotEmpty) {
B2CAccessToken? token = await AzureB2C.getAccessToken(subjects[0]);
if (!mounted || token == null) return;
final encodedData = token.token.split('.')[1];
final data =
utf8.fuse(base64).decode(base64.normalize(encodedData));
final claims = Claims.fromJson(jsonDecode(data));
var m = Provider.of<LoginModel>(context, listen: true);
m.logIn(claims); //<-- debugger never reaches this line
}
}
#override
Widget build(BuildContext context) {
// It is possible to register callbacks in order to handle return values
// from asynchronous calls to the plugin
AzureB2C.registerCallback(B2COperationSource.INIT, (result) async {
if (result.reason == B2COperationState.SUCCESS) {
_configuration = await AzureB2C.getConfiguration();
if (!mounted) return;
await checkLogin(context);
}
});
AzureB2C.registerCallback(B2COperationSource.POLICY_TRIGGER_INTERACTIVE,
(result) async {
if (result.reason == B2COperationState.SUCCESS) {
if (!mounted) return;
await checkLogin(context);
}
});
// Important: Remeber to handle redirect states (if you want to support
// the web platform with redirect method) and init the AzureB2C plugin
// before the material app starts.
AzureB2C.handleRedirectFuture().then((_) => AzureB2C.init("auth_config"));
const String assetName = 'assets/images/logo.svg';
final Widget logo = SvgPicture.asset(
assetName,
);
return SafeArea(
child: //omitted,
);
}
}
I opened an issue as well, but it did not help me.

Answer 1

Try this
var m = Provider.of<LoginModel>(context, listen: false)._claims;
You are using the Provider syntax but not doing anything really with it. You need to set it like this Provider.of<LoginModel>(context, listen: false).login(claims) and call it like this Provider.of<LoginModel>(context, listen: false)._claims;

Answer 2

I fixed it, moving the callback registrations from the build method to the initState method.