navigate to new route from model about scoped_model HOT 7 CLOSED

import 'package:flutter/material.dart';
import 'package:scoped_model/scoped_model.dart';

void main() {
  runApp(MyApp(
    model: NavigationModel(),
  ));
}

class MyApp extends StatelessWidget {
  final NavigationModel model;

  const MyApp({Key key, @required this.model}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ScopedModel<NavigationModel>(
      model: model,
      child: MaterialApp(
        title: 'Navigation Demo',
        home: LoginScreen('Login'),
      ),
    );
  }
}

class NavigationModel extends Model {
  bool _navigate = false;

  bool get navigate => _navigate;

  void onSubmit(String username, String password) {
    // perform some validation, call a backend, etc.
    // Then, if all that succeeds:
    _navigate = true;
    notifyListeners();
  }
}

class LoginScreen extends StatefulWidget {
  final String title;

  LoginScreen(this.title);

  @override
  LoginScreenState createState() {
    return new LoginScreenState();
  }
}

class LoginScreenState extends State<LoginScreen> {
  final emailController = TextEditingController();
  final passwordController = TextEditingController();

  // You cannot access the scoped model in the `initState` function because the
  // `context` variable has not been established. Therefore, you need to access
  // it in the `didChangeDependencies` method.
  //
  // Note: This function can be called several times, but adding the exact same
  // listener (the _navigationListener method) to the model will not result
  // in the function being called multiple times when the data changes.
  @override
  void didChangeDependencies() {
    ScopedModel.of<NavigationModel>(context).addListener(_navigationListener);
    super.didChangeDependencies();
  }

  @override
  void dispose() {
    // Make sure to clean up after ourselves by removing the listener!
    ScopedModel.of<NavigationModel>(context)
        .removeListener(_navigationListener);

    // Also dispose of the controllers...
    emailController.dispose();
    passwordController.dispose();
    super.dispose();
  }

  // This function will be run every time the model changes! We will use it to
  // check the navigate boolean. If it's set to true, we'll push a new screen!
  //
  // If not, we won't do anything.
  void _navigationListener() {
    if (ScopedModel.of<NavigationModel>(context).navigate) {
      // In this case, since it's a login Screen and we don't want the user to
      // go "Back" to it, we push a replacement
      Navigator.of(context).pushReplacement(
          MaterialPageRoute(builder: (context) => SecondScreen()));
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Column(
        children: <Widget>[
          TextField(
            controller: emailController,
            decoration: InputDecoration(hintText: 'Email'),
          ),
          TextField(
            controller: passwordController,
            decoration: InputDecoration(hintText: 'Password'),
          ),
          RaisedButton(
            child: Text('Login'),
            onPressed: () => ScopedModel.of<NavigationModel>(context)
                .onSubmit(emailController.text, passwordController.text),
          )
        ],
      ),
    );
  }
}

class SecondScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Second Screen'),
      ),
      body: Center(
        child: Text('Logged in!'),
      ),
    );
  }
}