Javafx pass login token from LoginController to CalendarController - javafx

Question

I am using Angela's framework for screens management and I am trying to write a very simple Calendar-application. While writing the UI and the controllers and using the aforementioned framework, all screens initialize immediately on program start. This means I have no idea when the user is actually looking at a certain view.
I need the login-token from the server (assigned in the LoginController) to fire a changed value event of some kind in the CalendarController that is currently running in the background (I presume). At the moment I don't know when the Calendar.fxml is visible and/if the user is logged in, and hence I don't know how to structure my logic to make a function start in CalendarController ONLY after the login-token has been set.
Been stuck a few days here, any help would be greatly appreciated. I have tried using an ObservableList and Listlistener-interface to no avail. Here is the respective part of my LoginController. TokenFactory is a class of static fields and methods (mostly trying to debug).
#FXML
public boolean login() throws JSONException, UnirestException {
if(validateUsernameField() && validatePasswordField()) {
HttpResponse<JsonNode> jsonResponse = Unirest.post(TokenFactory.getSERVER_ADR())
.field("username", usernameField.getText())
.field("password", passwordField.getText())
.asJson();
if ( ((String) jsonResponse.getBody().getObject().get("message")).equalsIgnoreCase("OK")) {
String token = ((String) jsonResponse.getBody().getObject().get("token"));
//Ignore JSON to debug
TokenFactory.setToken("fakeToken123");
responseLabel.setText("Logging in...");
myController.setScreen(ScreensFramework.CalendarID);
return true;
} else {
responseLabel.setText("Wrong username or password.");
passwordField.clear();
}
} return false;
}
//Screen management
ScreensController myController;

Answer 1

You have a bunch of options here:
First option: instead of loading all the screens at startup, just load the calendar screen when the login is successful. Then your CalendarController's initialize() method can basically assume the user is logged in.
Second option: modify the framework so that it either returns a reference to the controllers when it loads them, or gives you access to the controllers once loaded. The first version of this would look like:
public <T extends ControlledScreen> T loadScreen(String name, String resource) {
try {
FXMLLoader myLoader = new FXMLLoader(getClass().getResource(resource));
Parent loadScreen = (Parent) myLoader.load();
T myScreenControler = myLoader.getController();
myScreenControler.setScreenParent(this);
addScreen(name, loadScreen);
return myScreenControler ;
} catch (Exception e) {
System.out.println(e.getMessage());
return null;
}
}
Now when you first load the calendar screen, you can get a reference to its controller:
CalendarController calendarController = screensController.loadScreen(...);
so now when you are successfully logged in, you can invoke a method on the calendarController. Note the return type of loadScreen(...) has changed, so you may need to modify other code accordingly.
Alternatively, you could introduce a new map in ScreensController:
public class ScreensController extends StackPane {
private Map<String, Node> screens = new HashMap<>();
private Map<String, ControlledScreen> controllers = new HashMap<>();
// ...
public boolean loadScreen(String name, String resource) {
try {
FXMLLoader myLoader = new FXMLLoader(getClass().getResource(resource));
Parent loadScreen = (Parent) myLoader.load();
ControlledScreen myScreenControler = ((ControlledScreen) myLoader.getController());
myScreenControler.setScreenParent(this);
addScreen(name, loadScreen);
// also save the controller:
controllers.put(name, myScreenControler);
return true;
} catch (Exception e) {
System.out.println(e.getMessage());
return false;
}
}
// ...
// new method to retrieve controller:
public ControlledScreen getController(String name) {
return controllers.get(name);
}
// modify the remove method to clean up the controller as well:
public boolean unloadScreen(String name) {
if (screens.remove(name) == null) {
System.out.println("Screen didn't exist");
return false;
} else {
controllers.remove(name);
return true;
}
}
}
Now when the user logs in, you can do
CalendarController calendarController =
(CalendarController) myController.getController(ScreensFramework.CalendarID);
and invoke whatever method you need on calendarController.
Third option: create a BooleanProperty loggedIn = new SimpleBooleanProperty(); and just set it to true when the user is logged in. Then arrange for your CalendarController to be able to observe it and react when it changes. I like this option less, because arranging for the CalendarController to see the loggedIn property will almost certainly involve some kind of additional coupling between that controller and another class, but it is possible.