How do I use SharedPreferences in flutter?

Question

I am trying to get GoogleSign in working with a webapp in flutter, and for that I have been following an article. This is the function they said to use there for the login:

Future<String> signInWithGoogle() async {
  // Initialize Firebase
  await Firebase.initializeApp();

  final GoogleSignInAccount googleSignInAccount = await googleSignIn.signIn();
  final GoogleSignInAuthentication googleSignInAuthentication =
      await googleSignInAccount.authentication;

  final AuthCredential credential = GoogleAuthProvider.credential(
    accessToken: googleSignInAuthentication.accessToken,
    idToken: googleSignInAuthentication.idToken,
  );

  final UserCredential userCredential =
      await _auth.signInWithCredential(credential);
  final User user = userCredential.user;

  if (user != null) {
    // Checking if email and name is null
    assert(user.uid != null);
    assert(user.email != null);
    assert(user.displayName != null);
    assert(user.photoURL != null);

    uid = user.uid;
    name = user.displayName;
    userEmail = user.email;
    imageUrl = user.photoURL;

    assert(!user.isAnonymous);
    assert(await user.getIdToken() != null);

    final User currentUser = _auth.currentUser;
    assert(user.uid == currentUser.uid);

    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setBool('auth', true);

    return 'Google sign in successful, User UID: ${user.uid}';
  }

  return null;
}

It says that SharedPreferences is an undefined class. What does this do? Is it neccesary? If yes, how can I fix this? Thank you very much for your help, as this is my first time working with google sign-in in flutter web.

Solution 1

Add shared preference dependency in your pubspec.yaml file.

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.0
  shared_preferences: ^0.5.12+4

Now run flutter pug get. After getting the package import in your file like this,

import 'package:shared_preferences/shared_preferences.dart';

Now that should work fine.

Solution 2

1. open pubspec.yaml
2. add shared_preferences: ^0.5.12+4 below dependencies:
3. run flutter pub get
4. import 'package:shared_preferences/shared_preferences.dart';

here is link https://pub.dev/packages/shared_preferences/install

Comments

[jdsflk]

Did you add shared_dependencies to your pubspec.yaml?

[Bennett567]

No, where should I add it?

[Sagar Acharya]

if you have added the sharedprefrences in the pubspec.yaml some times the changed does not reflect in the project its better you restart the IDE and check again. Let me know if it works

[jdsflk]

In the dependencies section, here is the official guide of installation: pub.dev/packages/shared_preferences/install