UI.getCurrent().navigate does not display the wanted page when being called from setParameter(BeforeEvent beforeEvent, @OptionalParameter String s)

• Description: When using UI.getCurrent().navigate in a setParameter Method, the content of the page is not being displayed. I wanted to create some kind of fallback if no value for the given parameter has been found.

• Minimal reproducible example:

@Route(value = "shop", layout = MainLayout.class)
public class CompanyPage extends Composite<Div> implements HasUrlParameter<String> {

....

  @Override
    public void setParameter(BeforeEvent beforeEvent, @OptionalParameter String s) {
        company = companyRepository.getByCompanyLink(s);
        if (company == null) {
            //Rerturn to home if no company has been found.
            UI.getCurrent().navigate("");
        } else {
            getContent().add(new H1(company.getName()));
        }
    } 

• Expected behaviour: Should show the content of my page i wanted to navigate to.

• Actual behaviour: Shows nothing when trying to navigate to an other page then the value given in the Route of the class with the Parameter (example here: Shop). Something fails loading here.

[Legioth]

To change the navigation target during the navigation, you should use the rerouting feature,

What should I do in generic cases where the logic that wants to do the changing doesn’t know whether things happen during navigation or not?

Also, how is the developer supposed to know that they should use another method instead? Could we make navigate() throw with a helpful exception instead of silently doing the wrong thing?

[Legioth]

@ayash You can use one of the rerouteTo methods in the beforeEvent instance that is passed to setParameter.