beamer 1.0.0-nullsafety.6

A router that lets you navigate through guarded page stacks and URLs using the Navigator 2.0 API effortlessly.

Handle your application routing, synchronize it with browser URL and more. Beamer uses the power of Navigator 2.0 API and implements all the underlying logic for you.

---

• Key Concepts
  • Beaming
  • Updating
  • Beaming Back
• Examples
  • Books
  • Advanced Books
  • Deep Location
  • Location Builder
  • Guards
  • Beamer Widget
  • Integration with Navigation UI Packages
• Usage
  • On Entire App
  • Deeper in the Tree
  • General Notes
• Migrating
  • From 0.9 to 0.10
  • From 0.7 to 0.8
  • From 0.4 to 0.5
• Help and Chat
• Contributing

Key Concepts

The key concept of Beamer is a BeamLocation which represents a stack of one or more pages whose ordering and rebuild you control within pagesBuilder.

Beaming

You will be extending BeamLocation to define your app's locations to which you can then beam to using

Beamer.of(context).beamTo(MyLocation());

// or with an extension on BuildContext
context.beamTo(MyLocation());

or beam to a specific configuration of some location;

context.beamToNamed('/books/2');

// or more explicitly
context.beamTo(
  BooksLocation(
    pathBlueprint: '/books/:bookId',
    pathParameters: {'bookId': '2'},
  ),
);

You can think of it as teleporting (beaming) to another place in your app. Similar to Navigator.of(context).pushReplacementNamed('/my-route'), but Beamer is not limited to a single page, nor to a push per se. You can define an arbitrary stack of pages that get built when you beam there. Using Beamer can feel like using many of Navigator's push/pop methods at once.

You can carry an arbitrary key/value data in a location. This can be accessed from every page and updated as you travel through a location.

context.beamToNamed(
  '/book/2',
  data: {'note': 'this is my favorite book'},
);

Updating

Once at a BeamLocation, it is preferable to update the current location's state. For example, for going from /books to /books/3 (which are both handled by BooksLocation);

context.currentBeamLocation.update(
  (state) => state.copyWith(
    pathBlueprintSegments: ['books', ':bookId'],
    pathParameters: {'bookId': '3'},
  ),
),

Note that both beaming functions (beamTo and BeamToNamed) will have the same effect as update when you try to beam to a location which you're currently on, e.g. if you would to call context.beamToNamed('/books/3') instead of above code.

Beaming Back

All BeamLocations that you visited are kept in beamHistory. Therefore, there is an ability to beam back to the previous BeamLocation. For example, after spending some time on /books and /books/3, say you beam to /articles which is handled by another BeamLocation (e.g. ArticlesLocation). From there, you can get back to your previous location as it were when you left, i.e. /books/3;

context.beamBack();

Note that Beamer will remove duplicate locations from beamHistory as you go. For example, if you visit BooksLocation, ArticlesLocation and then BooksLocation again, the first instance of BooksLocation will be removed from history and beamHistory will be [ArticlesLocation,BooksLocation] instead of [BooksLocation,ArticlesLocation,BooksLocation]. You can turn that off by setting BeamerRouterDelegate.removeDuplicateHistory to false.

You can check whether you can beam back with context.canBeamBack or even inspect the location you'll be beaming back to: context.beamBackLocation.

---

Note that "Navigator 1.0" can be used alongside Beamer. You can easily push or pop pages with Navigator.of(context), but those will not be contributing to the URI. This is often needed when some info/helper page needs to be shown that doesn't influence the browser's URL. And of course, when using Beamer on mobile, this is a non-issue as there is no URL.

Examples

Books

Here is a recreation of books example from this article where you can learn a lot about Navigator 2.0. See Example for full application code of this example.

Advanced Books

For a step further, we add more flows to demonstrate the power of Beamer. The full code is available here.

Deep Location

You can instantly beam to a location in your app that has many pages stacked (deep linking) and then pop them one by one or simply beamBack to where you came from. The full code is available here. Note that beamBackOnPop parameter of beamTo might be useful here to override AppBar's pop with beamBack.

ElevatedButton(
  onPressed: () => context.beamTo(DeepLocation('/a/b/c/d')),
  // onPressed: () => context.beamTo(DeepLocation('/a/b/c/d'), beamBackOnPop: true),
  child: Text('Beam deep'),
),

Location Builder

You can override BeamLocation.builder to provide some data to the entire location, i.e. to all of the pages. The full code is available here.

// in your location implementation
@override
Widget builder(BuildContext context, Navigator navigator) {
  return MyProvider<MyObject>(
    create: (context) => MyObject(),
    child: navigator,
  );
}

Guards

You can define global guards (for example, authentication guard) or location guards that keep a specific location safe. The full code is available here.

• Global Guards

BeamerRouterDelegate(
  beamLocations: [
    HomeLocation(),
    LoginLocation(),
    BooksLocation(),
  ],
  guards: [
    BeamGuard(
      pathBlueprints: ['/books*'],
      check: (context, location) => AuthenticationStateProvider.of(context).isAuthenticated.value,
      beamTo: (context) => LoginLocation(),
    ),
  ],
),

• Location (local) Guards

// in your location implementation
@override
List<BeamGuard> get guards => [
  BeamGuard(
    pathBlueprints: ['/books/*'],
    check: (context, location) => location.pathParameters['bookId'] != '2',
    showPage: forbiddenPage,
  ),
];

Beamer Widget

Examples of putting Beamers into the Widget tree, when you need nested navigation.

• Bottom navigation example

class MyApp extends StatelessWidget {
  final _beamerKey = GlobalKey<BeamerState>();

  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routeInformationParser: BeamerRouteInformationParser(),
      routerDelegate: RootRouterDelegate(
        homeBuilder: (context, uri) => Scaffold(
          body: Beamer(
            key: _beamerKey,
            beamLocations: _beamLocations,
          ),
          bottomNavigationBar: BottomNavigationBarWidget(
            beamerKey: _beamerKey,
          ),
        ),
      ),
    );
  }
}

• Bottom navigation example with multiple Beamers (WIP)

class MyAppState extends State<MyApp> {
  int _currentIndex = 0;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: IndexedStack(
          index: _currentIndex,
          children: [
            Beamer(
              beamLocations: [ArticlesLocation()],
            ),
            Container(
              color: Colors.blueAccent,
              padding: const EdgeInsets.all(32.0),
              child: Beamer(
                beamLocations: [BooksLocation()],
              ),
            ),
          ],
        ),
        bottomNavigationBar: BottomNavigationBar(
          currentIndex: _currentIndex,
          items: [
            BottomNavigationBarItem(label: 'A', icon: Icon(Icons.article)),
            BottomNavigationBarItem(label: 'B', icon: Icon(Icons.book)),
          ],
          onTap: (index) => setState(() => _currentIndex = index),
        ),
      ),
    );
  }
}

• Nested navigation example

...

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routeInformationParser: BeamerRouteInformationParser(),
      routerDelegate: RootRouterDelegate(
        beamLocations: [
          HomeLocation(),
        ],
      ),
    );
  }
}

...


class HomeLocation extends BeamLocation {
  @override
  List<String> get pathBlueprints => ['/*'];

  @override
  List<BeamPage> pagesBuilder(BuildContext context) => [
        BeamPage(
          key: ValueKey('home'),
          child: HomeScreen(),
        )
      ];
}

...

class HomeScreen extends StatelessWidget {
  final _beamerKey = GlobalKey<BeamerState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home'),
      ),
      body: Row(
        children: [
          Container(
            color: Colors.blue[300],
            padding: const EdgeInsets.all(16.0),
            child: Column(
              children: [
                ElevatedButton(
                  onPressed: () => _beamerKey.currentState.routerDelegate
                      .beamToNamed('/books'),
                  child: Text('Books'),
                ),
                SizedBox(height: 16.0),
                ElevatedButton(
                  onPressed: () => _beamerKey.currentState.routerDelegate
                      .beamToNamed('/articles'),
                  child: Text('Articles'),
                ),
              ],
            ),
          ),
          Container(width: 1, color: Colors.blue),
          Expanded(
            child: Beamer(
              key: _beamerKey,
              beamLocations: [
                BooksLocation(),
                ArticlesLocation(),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

---

Integration with Navigation UI Packages

• Animated Rail Example, with animated_rail package.
• ... (contributions are very welcome; add your suggestion here or make a PR)

---

Usage

On Entire App

In order to use Beamer on your entire app, you must (as per official documentation) construct your *App widget with .router constructor to which (along with all your regular *App attributes) you provide

• routerDelegate that controls (re)building of Navigator pages and
• routeInformationParser that decides which URI corresponds to which Router state/configuration, in our case - BeamLocation.

Here you use the Beamer implementation of those - BeamerRouterDelegate and BeamerRouteInformationParser, to which you pass your BeamLocations.

class MyApp extends StatelessWidget {
  final routerDelegate = BeamerRouterDelegate(
    beamLocations: [
      HomeLocation(),
      BooksLocation(),
    ],
  );
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routerDelegate: routerDelegate,
      routeInformationParser: BeamerRouteInformationParser(),
      backButtonDispatcher:
          BeamerBackButtonDispatcher(delegate: routerDelegate),
    );
  }
}

Deeper in the Tree

Similar to above example, but we use RootRouterDelegate instead of BeamerRouterDelegate. Then, we have 2 options:

• provide homeBuilder to RootRouterDelegate which will serve the same role as MaterialApp.home. This is useful when you need a simple app with some navigation bar.

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routeInformationParser: BeamerRouteInformationParser(),
      routerDelegate: RootRouterDelegate(
        homeBuilder: (context, uri) => Scaffold(
          body: Beamer(
            beamLocations: _beamLocations,
          ),
          ...
        ),
      ),
      ...
    );
  }
}

• provide beamLocations to RootRouterDelegate as we would to BeamerRouterDelegate and have Beamer somewhere deep within those locations (see nested navigation example).

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routeInformationParser: BeamerRouteInformationParser(),
      routerDelegate: RootRouterDelegate(
        beamLocations: [
          HomeLocation(),
          BooksLocation(),
          ArticlesLocation(),
        ],
      ),
      ...
    );
  }
}

General Notes

• When extending BeamLocation, two methods need to be implemented; pathBlueprints and pagesBuilder.

  • pagesBuilder returns a stack of pages that will be built by Navigator when you beam there, and pathBlueprints is there for Beamer to decide which BeamLocation corresponds to which URI.
  • BeamLocation keeps query and path parameters from URI in its BeamState . The : is necessary in pathBlueprints if you might get path parameter from browser.

• BeamPage's child is an arbitrary Widgets that represent your app screen / page.

  • key is important for Navigator to optimize rebuilds. This should be a unique value for "page state".
  • BeamPage creates MaterialPageRoute, but you can extend BeamPage and override createRoute to make your own implementation instead.

Migrating

From 0.9 to 0.10

• BeamLocation constructor now takes only BeamState state. (there's no need to define special constructors and call super if you use beamToNamed)
• most of the attributes that were in BeamLocation are now in BeamLocation.state. When accessing them through BeamLocation;
  • pathParameters is now state.pathParameters
  • queryParameters is now state.queryParameters
  • data is now state.data
  • pathSegments is now state.pathBlueprintSegments
  • uri is now state.uri

From 0.7 to 0.8

• rename pages to pagesBuilder in BeamLocations
• pass beamLocations to BeamerRouterDelegate instead of BeamerRouteInformationParser. See Usage

From 0.4 to 0.5

• instead of wrapping MaterialApp with Beamer, use *App.router()
• String BeamLocation.pathBlueprint is now List<String> BeamLocation.pathBlueprints
• BeamLocation.withParameters constructor is removed and all parameters are handled with 1 constructor. See example if you need super.
• BeamPage.page is now called BeamPage.child

Help and Chat

For any problems, questions, suggestions, fun,... join us at Discord

Contributing

This package is still in early stages. To see the upcoming features, check the Issue board.

If you notice any bugs not present in issues, please file a new issue. If you are willing to fix or enhance things yourself, you are very welcome to make a pull request. Before making a pull request;

• if you wish to solve an existing issue, please let us know in issue comments first
• if you have another enhancement in mind, create an issue for it first so we can discuss your idea

Also, you can to speed up the development.