Flutter - How to pass user data to all views

Question

I\'m new to the flutter world and mobile app development and struggling with how I should pass user data throughout my app.

I\'ve tried several things, but none seem gre

Answer 1

I'd recommend investigating inherited widgets further; the code below shows how to use them with asynchronously updating data:

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

void main() {
  runApp(new MaterialApp(
      title: 'Inherited Widgets Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new Scaffold(
          appBar: new AppBar(
            title: new Text('Inherited Widget Example'),
          ),
          body: new NamePage())));
}

// Inherited widget for managing a name
class NameInheritedWidget extends InheritedWidget {
  const NameInheritedWidget({
    Key key,
    this.name,
    Widget child}) : super(key: key, child: child);

  final String name;

  @override
  bool updateShouldNotify(NameInheritedWidget old) {
    print('In updateShouldNotify');
    return name != old.name;
  }

  static NameInheritedWidget of(BuildContext context) {
    // You could also just directly return the name here
    // as there's only one field
    return context.inheritFromWidgetOfExactType(NameInheritedWidget);
  }
}

// Stateful widget for managing name data
class NamePage extends StatefulWidget {
  @override
  _NamePageState createState() => new _NamePageState();
}

// State for managing fetching name data over HTTP
class _NamePageState extends State<NamePage> {
  String name = 'Placeholder';

  // Fetch a name asynchonously over HTTP
  _get() async {
    var res = await http.get('https://jsonplaceholder.typicode.com/users');
    var name = json.decode(res.body)[0]['name'];
    setState(() => this.name = name); 
  }

  @override
  void initState() {
    super.initState();
    _get();
  }

  @override
  Widget build(BuildContext context) {
    return new NameInheritedWidget(
      name: name,
      child: const IntermediateWidget()
    );
  }
}

// Intermediate widget to show how inherited widgets
// can propagate changes down the widget tree
class IntermediateWidget extends StatelessWidget {
  // Using a const constructor makes the widget cacheable
  const IntermediateWidget();

  @override
  Widget build(BuildContext context) {
    return new Center(
      child: new Padding(
        padding: new EdgeInsets.all(10.0),
        child: const NameWidget()));
  }
}

class NameWidget extends StatelessWidget {
  const NameWidget();

  @override
  Widget build(BuildContext context) {
    final inheritedWidget = NameInheritedWidget.of(context);
    return new Text(
      inheritedWidget.name,
      style: Theme.of(context).textTheme.display1,
    );
  }
}

Answer 2

You can use the GetX package to check whether or not the user is logged in, get user data and have it accessible throughout your app

Answer 3

I crashed into another problem because of this problem you can check it out here So the solution I came up with is a bit untidy,I created a separate Instance dart page and imported it to every page.

 GoogleSignInAccount Guser = googleSignIn.currentUser;
 FirebaseUser Fuser;

I stored the user there on login and checked on every StateWidget if it was null

  Future<Null> _ensureLoggedIn() async {

if (Guser == null) Guser = await googleSignIn.signInSilently();
if (Fuser == null) {
  await googleSignIn.signIn();
  analytics.logLogin();
}
if (await auth.currentUser() == null) {
  GoogleSignInAuthentication credentials =
  await googleSignIn.currentUser.authentication;
  await auth.signInWithGoogle(
    idToken: credentials.idToken,
    accessToken: credentials.accessToken,
  );
}

This is my old code I did cleaned it up on my current app but I don't have that code now in handy. Just check out for null user and log it in again

I did it for most of the Firebase instances too because I have more than 3 pages on my app and Inherited Widgets was just too much work

Answer 4

For my lazy mathod, i just create new file like userdata.dart and then put any variable on it for example like dynamic Profile = null

inside userdata.dart

//only put this or anything u want.
dynamic Profile = null;

at startingpage.dart

//import that file
import '../userdata.dart';

class startingpage extends ...{
...
//set data to store..
   Profile = 'user profile';
...
}

to use the data just declare and use in anotherpage.dart

//import that file
import '../userdata.dart';

class anotherpage extends...{
...
}

class .. State ...{
...
//set the data to variable
   dynamic userdata = Profile;
   print('this is my lazy pass data' + userdata.toString());
...
}

Answer 5

I prefer to use Services with Locator, using Flutter get_it.

Create a UserService with a cached data if you like:

class UserService {
  final Firestore _db = Firestore.instance;
  final String _collectionName = 'users';
  CollectionReference _ref;

  User _cachedUser; //<----- Cached Here

  UserService() {
    this._ref = _db.collection(_collectionName);
  }

  User getCachedUser() {
    return _cachedUser;
  }

  Future<User> getUser(String id) async {
    DocumentSnapshot doc = await _ref.document(id).get();

    if (!doc.exists) {
      log("UserService.getUser(): Empty companyID ($id)");
      return null;
    }

    _cachedUser = User.fromDocument(doc.data, doc.documentID);
    return _cachedUser;
  }
}

Then create create a Locator

GetIt locator = GetIt.instance;

void setupLocator() {
  locator.registerLazySingleton(() => new UserService());
}

And instantiate in main()

void main() {
  setupLocator();
  new Routes();
}

That's it! You can call your Service + cachedData everywhere using:

.....
UserService _userService = locator<UserService>();

@override
void initState() {
  super.initState();
  _user = _userService.getCachedUser();
}