Save local string from a function inside shared preferences and use it in other pages - flutter

Question

I wish to save the userid string that am getting from a function that parses and decodes JWT token , and be able to use it in other pages in my Flutter app . I tried to save it inside shared preferences but doesn't seem to be working .This is my function and how I used shared preferences
String userName;
dynamic authenticator;
String _decodeBase64(String str) {
String output = str.replaceAll('-', '+').replaceAll('_', '/');
switch (output.length % 4) {
case 0:
break;
case 2:
output += '==';
break;
case 3:
output += '=';
break;
default:
throw Exception('Illegal base64url string!"');
}
return utf8.decode(base64Url.decode(output));
}
String _userid = '';
Map<String, dynamic> parseJwt(String token) {
final parts = token.split('.');
if (parts.length != 3) {
throw Exception('invalid token');
}
final payload = _decodeBase64(parts[1]);
final payloadMap = json.decode(payload);
if (payloadMap is! Map<String, dynamic>) {
throw Exception('invalid payload');
}
print(payload);
addStringToSF() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
_userid = payloadMap['user_id'];
prefs.setString('stringValue',_userid );
}
//print(payloadMap['user_id']);
return payloadMap;
}
getStringValuesSF() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
//Return String
String _userid = prefs.getString('userid');
print (_userid);
return _userid;
}
#override
void initState() {
super.initState();
getStringValuesSF();
}
authenticate() async {
// keyclock url : key-clock-url : example : http://localhost:8080
// my realm : name of your real.m
var uri = Uri.parse('http://169.254.105.22:8080/auth/realms/Clients');
// your client id
var clientId = 'helium';
var scopes = List<String>.of(['openid', 'profile']);
var port = 8080;
var issuer = await Issuer.discover(uri);
var client = new Client(issuer, clientId);
print(issuer.metadata);
urlLauncher(String url) async {
if (await canLaunch(url)) {
await launch(url, forceWebView: true);
} else {
throw 'Could not launch $url';
}
}
authenticator = new Authenticator(
client,
scopes: scopes,
port: port,
urlLancher: urlLauncher,
);
var c = await authenticator.authorize();
closeWebView();
var token = await c.getTokenResponse();
var userInformation = await c.getUserInfo();
setState(() {
userAccessToken = token.accessToken;
userName = userInformation.preferredUsername;
});
//print(token);
//return token;
parseJwt(userAccessToken);
}
I wish to use the userid variable here instead of the static string (id) am passing , in a way it dynamically reads the value from the function then use it inside the link to show the user's info :
final response = await http.get('http://169.254.105.22:8093/user/v1/users/d374169b-c61f-4a5a-b00a-2a2a8d9c4e19');
if (response.statusCode == 200) {
// If the server did return a 200 OK response,
// then parse the JSON.
return User.fromJson(jsonDecode(response.body));
} else {
// If the server did not return a 200 OK response,
// then throw an exception.
throw Exception('Failed to load user');
}
}
The second function is in another page (profile page), if anyone knows how I can save the userid from the function , then pass to another page (using sp or any other way) please don't hesitate to help thank you in advance

Answer 1

In my experience, when it comes to simple key/value storage, GetStorage is easier to use and less finicky than Shared Preferences. Try this:
Put this in your main before running your app.
await GetStorage.init();
Then your addStringToSF method would look like this:
addStringToSF() async {
final box = GetStorage();
_userid = payloadMap['user_id'];
box.write('stringValue', _userid);
}
Then from anywhere in your app access the stored value by
final box = GetStorage();
final newString = box.read('stringValue');
That should work for you.