Registering Routes Dynamically

In addition to registering routes and route templates using the @Route annotation, you can add and remove routes dynamically during runtime. This is useful when a route should be added or removed based on changed business data or application configuration at startup, for example.

The RouteConfiguration class allows you to configure routes to a specific scope. You can configure routes to:

  • All users using the application scope, or

  • Only certain active users using the session scope.

You can access the scope using the forSessionScope and forApplicationScope static methods. All components with an @Route annotation are added to the application scope.

Configuring User-specific Routes

You can add and remove routes for certain users, for example based on their access rights.

Example: Adding two views for currently active users.

RouteConfiguration.forSessionScope().setRoute("admin",
        AdminView.class);

// parent layouts can be given as a vargargs parameter
RouteConfiguration.forSessionScope().setRoute("home",
        HomeView.class, MainLayout.class);

A route set for the user can override a route with the same path from the application scope. This means that any statically registered @Route can be overridden for a specific user, if necessary.

The routes in the session scope are only accessible for the current user for as long as the session is valid. When the session is invalidated by the user logging out, the session-scoped routes are no longer available automatically. It is not necessary to specifically remove these routes.

When removing routes, you need to define precisely which route to remove.

Examples:

  • Removing a navigation target (AdminView.class) with all possible route aliases and route templates registered to it.

    RouteConfiguration configuration = RouteConfiguration
            .forSessionScope();
    // No view AdminView will be available
    configuration.removeRoute(AdminView.class);
  • Removing a path ("admin") which only removes the target mapped to it.

    // No path "admin" will be available
    configuration.removeRoute("admin");

For more related information, see:

Note
Removing a route in the session scope that had previously overridden a route in the application scope, makes the application-scoped route accessible once again.
Note
When dynamically registering a route, any annotations on the classes are ignored, except when the method used contains Annotated, for example setAnnotatedRoute. See Dynamic Registration of @Route Annotated Classes below for more.

Adding Routes on Application Startup

You can register routes during application startup using the ServiceInitLister.

Example: Using ServiceInitLister to register a route during deployment.

public class ApplicationServiceInitListener
        implements VaadinServiceInitListener {

    @Override
    public void serviceInit(ServiceInitEvent event) {
        // add view only during development time
        if (!event.getSource()
                .getDeploymentConfiguration()
                .isProductionMode()) {
            RouteConfiguration configuration =
               RouteConfiguration.forApplicationScope();

            configuration.setRoute("crud",
               DBCrudView.class);
        }
    }
}

Getting Registered Routes and Listening for Changes

When routes are registered dynamically, you may need to update UI components, like navigation menus, based on the added or removed routes.

You can retrieve the registered route templates using the getAvailableRoutes() method from the RouteConfiguration. To be notified of route changes, you can register a listener using the addRoutesChangeListener method.

Note
You should use the session registry to monitor changes, because it contains all the routes that are available for the current user.

Example: Getting available routes and registering a routes change listener.

RouteConfiguration configuration = RouteConfiguration
        .forSessionScope();
// add all currently available views
configuration.getAvailableRoutes()
        .forEach(menu::addMenuItem);

// add and remove menu items when routes are added and
// removed
configuration.addRoutesChangeListener(event -> {
    // ignoring any route alias changes
    event.getAddedRoutes().stream()
            .filter(route -> route instanceof RouteData)
            .forEach(menu::addMenuItem);
    event.getRemovedRoutes().stream()
            .filter(route -> route instanceof RouteData)
            .forEach(menu::removeMenuItem);
});

Adding Route Aliases for Dynamic Routes

When adding dynamic routes, the first route for which a navigation target is added is marked as the main route. The main route url is returned by the getUrl methods in a RouteConfiguration. Any additional registered route is seen as a route alias.

Example: Adding multiple routes as navigation targets in a RouteConfiguration.

RouteConfiguration configuration =
        RouteConfiguration.forSessionScope();
configuration.setRoute("main", MyRoute.class);
configuration.setRoute("info", MyRoute.class);
configuration.setRoute("version", MyRoute.class);

In this scenario, the configuration.getUrl(MyRoute.class) method returns main.

Example: Static class definition equivalent of the above route registration example.

@Route("main")
@RouteAlias("info")
@RouteAlias("version")
private class MyRoute extends Div {
}

If the "main" path is removed and an alias path remains available for use, the main path is updated to the first alias path found in the registry.

Warning
Be cautious when adding or removing routes from the ApplicationRouteRegistry, because this impacts every user of the system.

Dynamic Registration of @Route Annotated Classes

If you want to map all routes in the same way using the @Route annotation, you can configure the routes statically, but postpone registration until runtime.

To skip static registration on servlet initialization, add the registerAtStartup = false parameter to the @Route annotation. This prevents the route being registered on startup to the application-scoped registry. It also makes it easier to use existing parent chains and paths that are modified from the parent.

Example: Using the registerAtStartup parameter to postpone route registration.

@Route(value = "quarterly-report",
       layout = MainLayout.class,
       registerAtStartup = false)
@RouteAlias(value = "qr", layout = MainLayout.class)
public class ReportView extends VerticalLayout
        implements HasUrlParameter<String> {
    // implementation omitted
}

// register the above view during runtime
if (getCurrentUser().hasAccessToReporting()) {
    RouteConfiguration.forSessionScope()
            .setAnnotatedRoute(ReportView.class);
}

Example: Adding a New View on User Login

This example demonstrates how to add a new view on user login. Two types of users are available: admin users and normal users. After login, we show a different view, depending on the user’s access rights.

The demo application contains:

  • The LoginPage class that defines a statically registered route, "". This route is mapped to the login used for user authentication.

    @Route("")
    public class LoginPage extends Div {
    
        private TextField login;
        private PasswordField password;
    
        public LoginPage() {
            login = new TextField("Login");
            password = new PasswordField("Password");
    
            Button submit = new Button("Submit",
                    this::handleLogin);
    
            add(login, password, submit);
        }
    
        private void handleLogin(
                ClickEvent<Button> buttonClickEvent) {
        }
    }
  • The MainLayout class that contains a menu.

    public class MainLayout extends Div
            implements RouterLayout {
        public MainLayout() {
            // Implementation omitted, but could contain
            // a menu.
        }
    }
  • The InfoView class that defines the "info" route. This route is not statically registered, because it has the registerAtStartup = false parameter.

    @Route(value = "info", layout = MainLayout.class,
           registerAtStartup = false)
    public class InfoView extends Div {
        public InfoView() {
            add(new Span("This page contains info about "
                    + "the application"));
        }
    }

After login, we want to add a new route depending on the access rights of the user. Two targets are available:

  • AdminView class.

    public class AdminView extends Div {
    }
  • UserView class.

    public class UserView extends Div {
    }

In the LoginPage class, we handle adding to only the user session as follows:

private void handleLogin(
        ClickEvent<Button> buttonClickEvent) {
    // Validation of credentials is skipped

    RouteConfiguration configuration =
            RouteConfiguration.forSessionScope();

    if ("admin".equals(login.getValue())) {
        configuration.setRoute("", AdminView.class,
                MainLayout.class);
    } else if ("user".equals(login.getValue())) {
        configuration.setRoute("", UserView.class,
                MainLayout.class);
    }

    configuration.setAnnotatedRoute(InfoView.class);

    UI.getCurrent().getPage().reload();
}
  • A new target for the path "" is added to the session-scoped route registry. The new target overrides the application-scoped path "" for the user.

  • The InfoView class is added using the layout setup, configured using the @Route annotation. It is registered to the path "info" with the same MainLayout as the parent layout.

Note
Other users on other sessions still get Login for the "" path and cannot access "info".