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vaadin
Inconsistent behavior when forwarding to a view vs refresh
Description of the bug
Two example views: HelloWorldView and AboutView. AboutView accepts optional parameters. HelloWorldView forwards to AboutView with a String parameter.
@Route(value = "hello", layout = MainLayout.class)
public class HelloWorldView extends HorizontalLayout implements BeforeEnterObserver {
@Override
public void beforeEnter(BeforeEnterEvent event) {
event.forwardTo("about/123");
}
}
@Route(value = "about", layout = MainLayout.class)
public class AboutView extends VerticalLayout implements HasUrlParameter<String> {
@Override
public void setParameter(BeforeEvent event, @OptionalParameter String parameter) {
Notification.show("Got parameter: " + parameter);
}
}
If I navigate first to /hello, the URL gets updated to /about/123 but no Notification is shown. If I refresh the page with /about/123 in the URL bar, I get the notification "Got parameter: 123". I would expect the view's parameterized status to be the same if the URL doesn't change.
Expected behavior
The setParameter should fire even after the forwardTo with the needed parameter values.
Minimal reproducible example
Versions
- Vaadin / Flow version: 23.2.0
- Java version: n/a
- OS version: n/a
- Browser version (if applicable): n/a
- Application Server (if applicable): n/a
- IDE (if applicable):
@OlliTietavainenVaadin, if you use a breakpoint or sysout, I'm sure you'll see that setParameter(...) actually is called.
The issue here is that a forward (via a BeforeEvent) seems to cancel any notifications.
For me it's notifications that I open before the forward (from within setParameter(...)). But trying it with your example, even notifications after the forward (but still within the same request) don't work.
This started with Vaadin 23.2.0. 23.1.11 still works.
// Basically, when someone enters a view and encounters an error, I'll forward to the main view. But I'll show a notification so
// the user knows what's going on. After upgrading to 23.2.4 the notifications just stopped showing (which took a while to
// notice).
@Override
public void setParameter(BeforeEvent event, @OptionalParameter String parameter)
{
Notification.show("Notification");
event.forwardTo(OtherView.class);
}
Wrapping the notification in the following seems to be a suitable workaround:
event.getUI().access(() ->
{
Notification.show("Notification");
});
I've got a similar configuration, but with beforeEnter instead of setParameter and with some Span instances added to a VerticalLayout instead of a notification. In this case too the method is called, but the elements don't show up on the client side unless the page is reloaded. So this is not only an issue with notifications.
We are facing the same issue. The workaround https://github.com/vaadin/flow/issues/14570#issuecomment-1276199657 seams to be working fine
