Flutter clean navigation example

clean_navigation.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      onGenerateRoute: RouteGenerator.generateRoute,
      title: 'Navigation with Arguments',
      home: HomeScreen(),
    );
  }
}

class HomeScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home Screen'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            // A button that navigates to a named route.
            ElevatedButton(
              onPressed: () {
                Navigator.pushNamed(
                  context,
                  PlainScreen.route,
                );
              },
              child: Text('Navigate to screen without arguments passing'),
            ),
            SizedBox(height: 20),
            // A button that navigates to a named route.
            // For this route, extract the arguments in
            // the onGenerateRoute function and pass them
            // to the screen.
            ElevatedButton(
              onPressed: () {
                Navigator.pushNamed(
                  context,
                  PassArgumentsScreen.route,
                  arguments: ScreenArguments(
                    'Accept Arguments Screen',
                    'This message is extracted in the onGenerateRoute function.',
                  ),
                );
              },
              child: Text('Navigate to a named that accepts complex arguments'),
            ),
            SizedBox(height: 20),
            // When the user taps the button, navigate
            // to not existed route (error case)
            ElevatedButton(
              onPressed: () {
                Navigator.pushNamed(
                  context,
                  '',
                  arguments: ScreenArguments(
                    'Accept Arguments Screen',
                    'This message is extracted in the onGenerateRoute function.',
                  ),
                );
              },
              child: Text('Navigate to not-existed page'),
            ),
          ],
        ),
      ),
    );
  }
}

class PlainScreen extends StatelessWidget {
  static const route = '/plainScreen';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Plane Screen'),
      ),
      body: Center(child: Text('Plain screen without any parameters passed')),
    );
  }
}

// You can pass any object to the arguments parameter.
// In this example, create a class that contains both
// a customizable title and message.
class ScreenArguments {
  final String title;
  final String message;

  ScreenArguments(this.title, this.message);
}

// A Widget that accepts the necessary arguments via the
// constructor.
class PassArgumentsScreen extends StatelessWidget {
  static const route = '/passArguments';

  final ScreenArguments params;

  const PassArgumentsScreen({
    Key? key,
    required this.params,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(params.title),
      ),
      body: Center(
        child: Text(params.message),
      ),
    );
  }
}

// ROUTER CLASS. Contains all your navigation scheme
class RouteGenerator {
  static Route<dynamic>? generateRoute(RouteSettings settings) {
    final Object? args = settings.arguments;
    switch (settings.name) {
      case PlainScreen.route:
        return MaterialPageRoute(builder: (context) => PlainScreen());
      case PassArgumentsScreen.route:
        if (args is ScreenArguments) {
          // extract the required data from
          // the arguments and pass the data to the
          // correct screen.
          return MaterialPageRoute(
            builder: (context) {
              return PassArgumentsScreen(
                params: args,
              );
            },
          );
        }
    }
    return _generateErrorRoute();
  }

  static Route<dynamic> _generateErrorRoute() {
    return MaterialPageRoute(builder: (context) {
      return Scaffold(
        appBar: AppBar(
          title: Text('error'),
        ),
        body: Center(
          child: Text('error'),
        ),
      );
    });
  }
}