Flutter Google Sign In idToken expired - flutter

Question

I am using google_sign_in for auth in my flutter application.
I followed steps documented here to get started:
https://github.com/flutter/plugins/blob/master/packages/google_sign_in/google_sign_in/example/lib/main.dart
I get idToken as recommended to perform auth on the server side.
This is the code snippet I use to get idToken
_googleSignIn.onCurrentUserChanged.listen(
(GoogleSignInAccount account) {
setState(() {
developer.log("************Changing account");
_currentUser = account;
account.authentication.then((key){
developer.log("########### Changing token");
_userToken=key.idToken;
});
});
});
When I send idToken (_userToken in above example) it works fine for sometime, and later I see the following error message on the server side:
Token expired, 1593370077 < 1593384191
IT looks like token has an expiration time and expires after a while.
I tried moving above code snippet from initState() to build(). Here my assumption if I call it everytime when I am building the widget I should get a new token. THAT DIDN'T WORK
Reason I thought it might work was because when I "Run .dart" (not hot reload) it works. This made me assume moving it to build might work . It didn't work
My question: What is the programmatic way to refresh token, or get a new token in flutter using google_sign_in.
Thanks for your help!!

Answer 1

The idToken expires every 30 minutes.
To refresh the token you can either user the API or do a silent login like this:
Future<String> refreshToken() async {
final GoogleSignInAccount googleSignInAccount =
await googleSignIn.signInSilently();
final GoogleSignInAuthentication googleSignInAuthentication =
await googleSignInAccount.authentication;
final AuthCredential credential = GoogleAuthProvider.getCredential(
accessToken: googleSignInAuthentication.accessToken,
idToken: googleSignInAuthentication.idToken,
);
await auth.signInWithCredential(credential);
return googleSignInAuthentication.accessToken; //new token
}