Is there any way by which we can reload the whole SAPUI5 application?
When a SAPUI5 app is called, onInit() function is called and we are initializing some settings for view here. Say if some change (like selection of a checkbox in master view) requires the whole application to be reset, can we reload the application and call onInit() function again to correct our initial settings? Is there any trigger mechanism by which we can call onInit() function explicitly?
Thank you in advance for your suggestions.
Regards,
Raja
If you have the need to reload or reset your application, then I would think your app suffers from a major design flaw... This is definitely something I would look into first if I were you!
However, to answer your question, why not move the initialization code into its own function, and call that function from the onInit() event handler and whenever you need to reset your app?
I suggest you to use some kind of intercommunication (e.g.: EventBus) between your Controller instances, from the master view notify your Controllers to rerun initialization logic like follows:
move you initialization logic to separate functions on each Controller and call this method upon onInit
in onInit subscribe to reinitialize event
in you master view add a listener function to the mentioned checkbox selection event, and publish the reinitialize event to notify your Controllers to reinitialize
Controller.js:
function onInit() {
this._initialize();
EventBus.subscribe('reinitialize', this._initialize);
}
funcion _initialize() {
// init logic
}
MasterController.js:
function onSelectionChange() {
EventBus.publish('reinitialize');
}
Sometimes you cannot directly use the window global variable in sapui5.
Refer to this page:
https://help.sap.com/viewer/825270ffffe74d9f988a0f0066ad59f0/CF/en-US/7d0dba71a2cb45ebb1959daba904ca99.html?q=location%20reload
var myLocation = location;
myLocation.reload();
Related
I am creating an app that has multiple questions (like a quiz) and I am using Getx for state management.
in the main method I initialize controllers as follows
void main() {
Get.put(HomeScreenController());
Get.put(QuestionsController());
runApp(MyApp());
}
in the home screen I have a pageview and I am using HomeScreenController() to manage it.
The last page of the page view has a button to go back to the initial page. For my case, I want to reset all variables in both controllers to their initial values.
I have tried one solution, it worked but I feel like it is tedious to do for other controllers that has so many variables which is calling a method that reset the variables manually.
The other solution that I have tried is to dispose the controllers when the user clicks on the button calling Get.put(HomeScreenController()); in the build method of the home screen.
onPressed: () {
qCon.dispose();
controller.dispose();
Navigator.pushReplacementNamed(context, HomeWrapper.id);
},
but I got an error that says
A HomeScreenController was used after being disposed.
'Once you have called dispose() on a HomeScreenController, it can no longer be used.
is there anyway to do what I am trying to do other than updating variable manually?
Update: Turns out that
Get.reset();
do the job when initializing controllers in the home screen
also calling
Get.put(ControllerName());
in a build method will re-initialize the controller
I'm struggling to find a way to execute a function in the main controller when it loads. When the main controller is loaded the first time, I can get that function executed inside onInit. But the issue is when user logs out and logs back in the main controller, the method onInit does not get executed again. Is there a way to execute a function every time when controller loads?
Below code will help you to achieve what your are looking for
onInit: function() {
this.getRouter().getRoute("routeName").attachPatternMatched(this._onObjectMatched, this);
}
_onObjectMatched: function() {
//this function executes every time you navigate to this page
}
Demokit link for detailed information
What do you mean by "when user logout and log back in the Main Controller"?? When your app loads the view the first time, it executes the onInit, onBeforeRendering, onAfterRendering and other lifecycle events. But if you don't destroy the controller instance you never 'log out' of it. It remains there as an object in your DOM and their functions can be called whenever is needed.
Now, if you are using the UI5 Router to navigate back and forth to other views, then I suggest you to set 'PatternMatched' events in your router. This events will be fired whenever the given pattern is match, no matter if it is the 1st or the n-th time.
Check out:
read optional url parameters
Step 32: Routing with Parameters
What I would like to do is unsubscribe from events at the moment the ViewModel is no longer needed. I tried implementing IDisposable but nobody calls Dispose(), not Xamarin.Forms nor Prism.Forms.
We have an app created with Xamarin.Forms. We use Prism.Forms to do MVVM. When navigating to a new page (push on stack) Prism.Forms wires the ViewModel to the Page. When navigating back (pop from stack) the ViewModel gets GarbageCollected after a while.
The problem is however that at a point in time we have a couple of the same type of ViewModels with subscriptions to events that are not bound to a View. When the events fire all these ViewModels start doing their thing. So I am looking for a way to unsubscribe at the moment the subscription is no longer needed.
Does anyone have a solution?
You can make sure the Dispose() is called in the OnDisappearing() event of the View, if you want to ensure that ViewModel is not present anymore in the memory than the view.
It is better if you care only about subscribe and unsubscribe of events, then to do it in the OnAppearing() and OnDisappearing(). In that case you will be sure of no event handlers been present on the viewmodel once view is not visible.
Implement IDestructible or INavigationAware
(or both as in BaseViewModelsample from Prism).
Depending on your object lifecycle :
Implement your disposal code in the Destroy method of IDestructible interface.
Implement your disappearing/appearing code in the OnNavigatedFrom/OnNavigatedTo methods on INavigationAware interface.
Bonus:
IDestructible can be implemented also by the View (and it will called accordingly by Prism when the view is destroyed).
Note:
While the solution above using OnAppearing/OnDisappearing works, it induces that ViewModel will depends on a call from View for managing its lifecycle (not clean). Moreover these methods don't exist on ContentView.
I have a RCP application with different views. The views should interact with each other through the Eclipse SelectionService.
In view 1 I have added a SelectionListener with
getSite().getWorkbenchWindow().getSelectionService().addSelectionListener(this.listener);
In view 2 I have added a SelectionProvider with
getSite().setSelectionProvider(this);
To get this working, I implemented the methods from the IInputSelectionProvider in view 2. When I run my program, view 1s selection listener is not invoked. After debugging,
I found out that view 1 is not added in the list of listeners of view 2. In view 2 I have a method
private ListenerList listenersList = new ListenerList();
#Override
public void addSelectionChangedListener(ISelectionChangedListener iselectionchangedlistener) {
// TODO Auto-generated method stub
listenersList.add(iselectionchangedlistener);
}
which adds listeners to the IInputSelectionProvider. My question is: Who should call this method. My understanding is that Eclipse SelectionService should does this with
getSite().getWorkbenchWindow().getSelectionService().addSelectionListener(this.listener);
But it doesn't work. Do I have to fill the listenerList by myself? If yes, why do I have to use the SelectionService at all?
Or do I have to iterate through the list of listeners by calling any other method and not using the list at all? Because if I inspect the ISelectionService object
ISelectionService service = getSite().getWorkbenchWindow().getSelectionService();
I see all the listeners.
But they are not part of the listenerList above.
The addSelectionChangedListener is called every time a view gets activated and removed when a view is not longer active. This means: If View A is active and 'setSeletion' is called, all views which are listening are notified. If these views by themselves call 'setSelection' nothing happens. No notification is started.
Does Android have an equivalent to Cocoa's viewDidLoad and viewDidAppear functions?
If not, then how would I go about performing an action when a View appears? My app is a tabbed application, in which one of the tabs is a list of forum topics. I would like the topic list to be refreshed every time the view appears. Is such a thing possible in Android?
The Activity class has onCreate and onResume methods that are pretty analagous to viewDidLoad and viewDidAppear.
Activity.onResume
EDIT
To add to this, since some have mentioned in the comments that the view tree is not yet fully available during these callbacks, there is the ViewTreeObserver that you can listen to if you need first access to the view hierarchy. Here is a sample of how you can use the ViewTreeObserver to achieve this.
View someView = findViewById(R.id.someView);
final ViewTreeObserver obs = someView.getViewTreeObserver();
obs.addOnPreDrawListener(new OnPreDrawListener() {
public boolean onPreDraw() {
obs.removeOnPreDrawListener(this);
doMyCustomLogic();
return true;
}
});
onResume() is more like viewCouldAppear. :) public void onWindowFocusChanged(boolean) is the closest to viewDidAppear. At this point within the activity lifecycle you may ask the view about its size.
From my limited, nascent understanding of Android, you implement viewDidLoad type functionality in the onCreate method of your Activity:
onCreate(Bundle) is where you
initialize your activity. Most
importantly, here you will usually
call setContentView(int) with a layout
resource defining your UI, and using
findViewById(int) to retrieve the
widgets in that UI that you need to
interact with programmatically.
The equivalent for viewDidAppear is closer to the onResume method:
Called after
onRestoreInstanceState(Bundle),
onRestart(), or onPause(), for your
activity to start interacting with the
user. This is a good place to begin
animations, open exclusive-access
devices (such as the camera), etc.