Flutter/Dart: How to make a Boolean Listenable with the ChangeNotifierProvider?

Question

I'm using a ChangeNotifierProvider to provide a boolean which returns true or false depending on whether the user is logged in. How do I make the boolean listenable so that provider updates it automatically when the user logs in/out?

Widget build(BuildContext context) {
var socialProvider = Provider.of<SocialProvider>(context);
return Container(  
           child: new FlatButton(
           onPressed: () {
               if (
                  socialProvider.currentlogged != true
                  ) {                        
       Do something
             } else {
        Do something else
                      },
),}

Answer 1

Best way to implement authentication functionality using provider is by wrapping your parent class with Provider. For example,

MultiProvider(
    providers: [
      ChangeNotifierProvider(
        create: (_) => Authentication(),
      ),
      )
    ],
    child: MaterialApp(
          ........
    ),

In this way you can consume the provider anywhere from the app just by wrapping child widget with Consumer.

Consumer<Authentication>(
      builder: (context, auth, _) => Container(  
       child: new FlatButton(
       onPressed: () {
           if (auth.currentlogged != true) {                        
             Do something
         } else { 
             Do something else
         }

Since authentication controls the entire app itself I wrapped MaterialApp with Provider you can do it in any widget so that all of its children can consume it. When you call notifyListeners(); in a provider, it will re-render the whole consumer part.