How can I reload my page to redirect to an URI Fragment in VAADIN? - redirect

Question

In my Vaadin webapp I have a tipical architecture with login. In some cases, the user can access directly to some resources using Vaadin URI Fragments (http://example.com/#fragment).
When a user tryes to access some resource, If the user has logged in, I take from the URL the #FRAGMENT and I bring him to it.
But if the user has no logged in, when he logs in I used to bring him to the main page using
getPage().open("/", "_self");
but since if I add an URI Fragment, the getPage().open(...) does not work.
Is there any way to redirect the user to a correct URL (URL with UriFragment in my case) from code?

Answer 1

Note that there is a fundamental difference in how navigation is handled in traditional web applications versus single-page applications as implemented with Vaadin. In traditional web applications you navigate through the app by making full HTTP GET-Requests on some path (such as www.example.com/myapp/home). On each such request, a full page reload is performed. You can't do that with Vaadin, as a full page reload means reloading the Vaadin widget set and rebuilding the page layout from the ground up. Therefore, single-page applications typically use the URI fragment for navigation purposes. Changes to this fragment are solely handled by the client-side JavaScript code. There will be no GET-Request induced by the browser when the URI fragment is changed.
That's why the approach you described doesn't work for you. Using Page.open(...) will open a web page through a HTTP GET-Request resulting in a complete reload of your Vaadin application.
The solution for your problem is to solely handle all navigation (including state-dependent redirects) through the Page object's URI fragment handling methods (or through the [Navigator][1] component). Redirecting in Vaadin can be achieved by programmatically setting the URI fragment with Page#setUriFragment() or Navigator#navigateTo() and having your URI handling code (or Navigator) take care of the rest. Only then it is assured that your users stay on the same page even when they are redirected to a login form or to some other place after logging in.

Answer 2

I would like to add to Roland's answer and share how I solved this.
My UI:
#Override
protected void init(VaadinRequest request) {
setSizeFull();
setContent(masterView);
getPage().addUriFragmentChangedListener(event -> present(event.getUriFragment()));
present(getPage().getUriFragment());
}
The masterView is just a CustomComponent that has a content section. When the menu is clicked, I simply setContent to the masterView's content section. Swapping out the middle, basically.
present method:
private void present(String fragment) {
masterView.setContent(getComponentFromFragment(fragment));
}
Finally:
private Component getComponentFromFragment(String fragment) {
if (fragment.equals(someOtherView.NAME))
return someOtherView;
return null; // null clears it out as in the welcome page
}
The important part is the present in the init. When the UI renders for the first time and fires the init, it goes ahead and grabs whatever the URI fragment is in the browser and presents that as well.
Works great.

Answer 3

Maybe this can work:
UI.getCurrent().getPage().executeJavaScript("window.location.href = 'http://google.com'");