Simple route generator that exposes arguments and query params to route builders

example.dart

main() {
  BuildContext context;

  final router = NavigationService(context);

  return MaterialApp(
    onGenerateRoute: (settings) => router.handleGenerateRoute(
      settings,
      routes: {
        '/': (params, context) => HomeView(),

        /// You can get here with a few methods
        ///
        /// 1) Navigator.of(context).push('/inbox')
        /// 2) Navigator.of(context.push('/inbox?thread_id=foo'))
        /// 3) Navigator.of(context.push('/inbox', arguments: {'thread_id': 'foo'}))
        ///
        /// 4) router.to('/inbox')
        /// 5) router.to('/inbox?thread_id=foo')
        /// 6) router.to('/inbox', {'thread_id': 'foo'})
        '/inbox': (params, context) {
          final threadId = params['thread_id'];

          if (threadId != null)
            return InboxView(threadId: threadId);
          else
            return InboxView();
        }
      },
    ),
  );
}

navigation_service.dart

class NavigationService {
  /// An opinionated navigation service that exposes methods for simple navigation
  /// on web/desktop.
  NavigationService(this.context);

  /// The context used to get [Navigator] from [MaterialApp]
  final BuildContext context;

  /// Navigate to a path on web/desktop with optional string arguments
  Future<T> to<T>(String path, {Map<String, String> arguments}) {
    return Navigator.of(context)
        .pushReplacementNamed(path, arguments: arguments);
  }

  /// Connect this to [MaterialApp.onGenerateRoute] along with a fallback route
  /// string and a list of routes.
  ///
  /// Will parse query params, ie `/inbox?foo=42` and pass `{"foo":"42"}` to
  /// `/inbox` route. Will also merge [RouteSettings.arguments] if they are of
  /// the type `Map<String, String>`
  Route<dynamic> handleGenerateRoute(
    RouteSettings settings, {
    String fallbackRoute = '/',
    @required Map<String, RouteBuilder> routes,
  }) {
    /// Parse the route to extract query params
    final uri = Uri.tryParse(settings.name);

    /// Build params from query params and route arguments
    final params = <String, String>{
      /// Path parameters
      ...uri.queryParameters,

      /// Route arguments if it's a `Map<String, String>`
      if (settings.arguments is Map<String, String>)
        ...settings.arguments as Map<String, String>,
    };

    final route = uri.path;

    /// Get the route, or fallback to the previous route
    final builder = routes[route] ?? routes[fallbackRoute];

    if (builder == null)
      throw StateError(
          "Couldn't find route $route or the fallback route $fallbackRoute");

    return MaterialPageRoute(
      settings: settings,
      builder: (context) => builder(params, context),
    );
  }
}

typedef RouteBuilder = Widget Function(
    Map<String, String> params, BuildContext context);