AppLayout as annotation and HasUrlParameter

Flow
1

Hi,

I have a view as entrypoint of my application which navigates to the first view with a parameter:

@Route("")
public class ViewStart extends VerticalLayout {
    public ViewStart() {
	    super();
	    add(new Button("Start", e -> getUi().ifPresent(ui -> ui.navigateTo(View1.class, "foobar"))));
	}
}

There are two views with HasUrlParameter:

@Route("view1", layout = MyLayout.class)
public class View1 extends VerticalLayout implements HasUrlParameter<String> {
    @Override
    public void setParameter(BeforeEvent be, @OptionalParameter String param) {
        Notification.show(param);
    }
}

@Route("view2", layout = MyLayout.class)
public class View2 extends VerticalLayout implements HasUrlParameter<String> {
    @Override
    public void setParameter(BeforeEvent be, @OptionalParameter String param) {
        Notification.show(param);
    }
}

And the layout which is only used by my views has have a parameter:

public class MyLayout extends AppLayout {
    public MyLayout() {
	    super();
		Tabs menu = createMenu();
		addToNavbar(true, menu);
	}
	
	private Tabs createMenu() {
	    String param = retrieveParam();
		
		Tabs tabs = new Tabs();
		Tab tab1 = new Tab(new RouterLink("View1", View1.class, param));
		Tab tab2 = new Tab(new RouterLink("View2", View2.class, param));
		return tabs;
	}
	
	private String retrieveParam() {
	    // How do i retrieve the url-param in the layout to use it in the navbar?
	}
}

My problem is the retrieveParam() method in the layout:

  • the layout doesn’t know anything about the HasUrlParameter of its views
  • if I remember correctly I didn’t have access to the current request during instantiation
  • the navbar has to be created during instantion
  • the href in the RouterLink can’t be easily replaced with a new class-target and parameter after initial creation

I tried some solutions with VaadinServletRequest req = (VaadinServletRequest) VaadinService.getCurrentRequest();, etc but it feels quite unstable.
I don’t want to store the value in the session since i want to provide direct access via url to the view with .../view1/my-param.

How can I resolve this and respect the current parameter of the view in the navbar of its layout?

To clarify:
((VaadinServletRequest) VaadinRequest.getCurrent()).getRequestURI() seemed like the best idea, but on the initial request to e.g. enter View1 it still contains the URI of the StartView.

2

My current working solution is implementing BeforeEnterObserver to my layout.
There i grab the parameter from the segments of event.location().getSubLocation() and creating the navbar after that instead of using the constructor.

Maybe someone has a better solution but I guess this might work for now.