Flutter Shared Preferences Auth FIle - dart

Question

I'm trying to write an auth file, with a list of finals with shared preferences values in it. I could import that auth file in my other files and i could get like the name or email without importing shared preferences in every file.
It would probably look way smoother and cleaner.
I thought something like this would have worked but it didn't
/// ------------Auth------------ ///
final email = getEmail();
getEmail() async {
final SharedPreferences prefs = await SharedPreferences.getInstance();
return prefs.getString('email');
}
Does anybody have any idea how to do this?
Greetings,
Jente

Answer 1

I assume you want to use the method in multiple files. The problem with your code is that the getEmail method is marked async that means it will have to return a Future. Think about it like this, when you mark a method as async it means it will return something (or finish executing) in the near future. When ? Well you don't know exactly when, so you'll need to get "notified" when the method is "done", that's why you'll use a Future. Something like this:
Future<String> getEmail() async {
final SharedPreferences prefs = await SharedPreferences.getInstance();
return prefs.getString('email');
}
class ThisIsTheClassWhereYouWantToUseTheFunction {
//let's say you have a method in your class called like the one below (it can be any other name)
void _iNeedTheEmailToPrintIt() {
//this is the way you can call the method in your classes, this class is just an example.
getEmail().then((thisIsTheResult){ // here you "register" to get "notifications" when the getEmail method is done.
print("This is the email $thisIsTheResult");
});
}
}

Answer 2

you can define a class Auth or much better a scoped_model.
Here's a class implementation
class Auth {
get email() {
final SharedPreferences prefs = await SharedPreferences.getInstance();
return prefs.getString('email');
}
set email(String em) {
final SharedPreferences prefs = await SharedPreferences.getInstance();
pref.setString('email', em);
}
}
and now you can call it in your widgets :)

Answer 3

Try this;
make dart file (Filename and Class Name ShareUtils)
add follow Code
import 'package:shared_preferences/shared_preferences.dart';
import 'dart:async';
class ShareUtils {
static ShareUtils _instance;
SharedPreferences ShareSave;
factory ShareUtils() => _instance ?? new ShareUtils._();
ShareUtils._();
void Instatce() async {
ShareSave = await SharedPreferences.getInstance();
}
Future<bool> set(key, value) async {
return ShareSave.setString(key, value);
}
Future<String> get(key) async {
return ShareSave.getString(key);
}
}
2.Add main.dart
class MyApp extends StatelessWidget {
static ShareUtils shareUtils;
#override
Widget build(BuildContext context) {
ThemeData mainTheme = new ThemeData(
);
shareUtils = new ShareUtils();
shareUtils.Instatce();
MaterialApp mainApp = new MaterialApp(
title: "Your app",
theme: mainTheme,
home: new SplashPage(),
debugShowCheckedModeBanner: true,
routes: <String, WidgetBuilder>{
"RegisterPage": (BuildContext context) => new RegisterPage(),
"HomePage": (BuildContext context) => new HomePage(),
},
);
return mainApp;
}
}
3.SET
void UserInfo(code, token) async{
await MyApp.shareUtils.set("token", token);
await MyApp.shareUtils.set("code", code);
await Navigator.of(context).pushNamed("HomePage");
}
4.GET
Future NextPage() async {
MyApp.shareUtils.get("token").then((token) {
print(token);
if (token == null || token == "") {
Navigator.of(context).popAndPushNamed("RegisterPage");
} else {
Navigator.of(context).popAndPushNamed("HomePage");
}
});
}
Hope to help.