ABOUT ME

-

Today
-
Yesterday
-
Total
-
  • Flutter BLoC, Scoped Instances
    lang/dart 2020. 9. 16. 08:30

    Flutter BLoC, inheritedWidget Provider

    main.dart

    import 'package:flutter/material.dart';
    import 'src/app.dart';
    
    void main() => runApp(App());

    src/app.dart

    import 'package:flutter/material.dart';
    import 'screens/login_screen.dart';
    import 'blocs/provider.dart';
    
    class App extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return Provider(
          child: MaterialApp(
            title: 'Login',
            home: Scaffold(
              appBar: AppBar(
                title: Text('LoginForm'),
              ),
              body: LoginScreen(),
            ),
          ),
        );
      }
    }

    src/screens/login_screen.dart

    import 'package:flutter/material.dart';
    import '../blocs/bloc.dart';
    import '../blocs/provider.dart'; // Different Code of "Single Global Instance"
    
    class LoginScreen extends StatefulWidget {
      @override
      _LoginScreenState createState() => _LoginScreenState();
    }
    
    class _LoginScreenState extends State<LoginScreen> {
      @override
      Widget build(BuildContext context) {
        final bloc = Provider.of(context); // Different Code of "Single Global Instance"
    
        return Container(
          margin: EdgeInsets.all(8.0),
          child: Form(child: 
            Column(children: <Widget>[
              fieldEmail(bloc), // Different Code of "Single Global Instance"
              fieldPassword(bloc), // Different Code of "Single Global Instance"
              _submit(),
              ],
            ),
          ),
        );
      }
    
      Widget fieldEmail(Bloc bloc) { // Different Code of "Single Global Instance"
        return StreamBuilder(
          stream: bloc.email,
          builder: (context, snapshot) {
            return TextField(
              onChanged: bloc.changeEmail,
              keyboardType: TextInputType.emailAddress,
              decoration: InputDecoration(
                labelText: 'Email',
                hintText: 'useanem@domain.com',
                errorText: snapshot.error,
              ),
            );
          }
        );
      }
    
      Widget fieldPassword(Bloc bloc) { // Different Code of "Single Global Instance"
        return StreamBuilder(
          stream: bloc.password,
          builder: (context, snapshot) {
            return TextField(
              onChanged: bloc.changePassword,
              obscureText: true,
              decoration: InputDecoration(
                labelText: 'Password',
                hintText: 'over 3 charactor',
                errorText: snapshot.error,
              ),
            );
          }
        );
      }
    
      Widget _submit() {
        return RaisedButton(
          color: Colors.blue,
          child: Text('Submit', style: TextStyle(color: Colors.white),),
          onPressed: (){
            print('onPressed Submit');
          },
        );
      }
    }

    src/blocs/bloc.dart

    import 'dart:async';
    import 'validators.dart';
    
    class Bloc extends Object with Validators {
      final _email = StreamController<String>();
      final _passwd = StreamController<String>();
    
      Stream<String> get email => _email.stream.transform(validatorEmail);
      Stream<String> get password => _passwd.stream.transform(validatorPassword);
    
      Function(String) get changeEmail => _email.sink.add;
      Function(String) get changePassword => _passwd.sink.add;
    
      dispose() {
        _email.close();
        _passwd.close();
      }
    }
    
    // Different Code of "Single Global Instance"
    // final bloc = Bloc();

    src/blocs/provider.dart

    import 'package:flutter/material.dart';
    import 'bloc.dart';
    
    class Provider extends InheritedWidget {
      final bloc = Bloc();
    
      Provider({key, Widget child}) : super(key: key, child: child);
    
      // @override
      // bool updateShuldNotify(_) => true;
      @override
      bool updateShouldNotify(InheritedWidget oldWidget) => true;
      /*{
        // TODO: implement updateShouldNotify
        throw UnimplementedError();
      }*/
    
      static Bloc of(BuildContext context) {
        // ignore: deprecated_member_use
        // return (context.inheritFromWidgetOfExactType(Provider) as Provider).bloc;
        // https://stackoverflow.com/a/59304297
        return (context.dependOnInheritedWidgetOfExactType<Provider>()).bloc;
      }
    }

    src/blocs/validators.dart

    import 'dart:async';
    
    class Validators {
      final validatorEmail = StreamTransformer<String, String>.fromHandlers(
        handleData: (String email, sink) {
          if( email.contains('@') ){
            sink.add(email);
          } else {
            sink.addError('Enter a valid email');
          }
        }
      );
    
      final validatorPassword = StreamTransformer<String, String>.fromHandlers(
        handleData: (String passwd, sink) {
          if( passwd.length >= 3 ) {
            sink.add(passwd);
          } else {
            sink.addError('password must be at leat 3 characters');
          }
        }
      );
    }

    Flutter State

    'lang > dart' 카테고리의 다른 글

    Flutter BLoC, RxDart combineLatestStream BehaviorSubject On Submit  (0) 2020.09.18
    Flutter BLoC, RxDart combineLatestStream  (0) 2020.09.17
    Flutter BLoC, Scoped Instances  (0) 2020.09.16
    Flutter BLoC, Single Global Instance  (0) 2020.09.15
    Flutter BLoC  (0) 2020.09.14
    Dart BLoC Pattern  (0) 2020.09.11

    댓글 0

Designed by Tistory.