I have added code that I would believe should remove an event handler of an acumatica base class.
public override void Initialize()
{
// Remove the event handler on the APTran object for APTran_SubID_FieldDefaulting so we can override it in this module
Base.FieldDefaulting.RemoveHandler<APTran.subID>(A PTran_SubID_FieldDefaulting);
}
Yet, it still runs through the base code. If I remove this code and keep my new event handler, it runs through the event handler I have and then also appears to run through the Base event handler.
Any suggestions on how to remove the base event handler so it will just use the new event handler?
Solution
Turns out (thanks go to Ivan)
that I do not need to remove the event handler, I just need to declare the event handler in the extension with a third parameter that points back to the original event handler, then I can choose to not call that delegate if that is what I need in my project.
example:
protected void APTran_SubID_FieldDefaulting(PXCache sender, PXFieldDefaultingEventArgs e, PXFieldDefaulting del)
{
APTran row = (APTran)e.Row;
if (row == null) { return; }
// do my code here
// skip calling the original event
//del.Invoke(sender, e); -- invokes the Base FieldDefaulting event handler
}
Related
The following diagram appears in the Android Jetpack ViewModel Overview:
Why does the upper onDestroy graphic in the middle column have a pointy end and not terminate the ViewModel Scope while the other onDestroy graphic has a square end and terminate the ViewModel Scope?
I was able to get in touch with the creator of the diagram, Jose Alcérreca, who told me "the second onDestroy doesn't have an arrow is because it's the end of the activity's lifecycle (triggered by finish() not a recreation)."
I was also pointed to the source code for ComponentActivity, which shows the observer for ON_DESTROY:
getLifecycle().addObserver(new LifecycleEventObserver() {
#Override
public void onStateChanged(#NonNull LifecycleOwner source,
#NonNull Lifecycle.Event event) {
if (event == Lifecycle.Event.ON_DESTROY) {
// Clear out the available context
mContextAwareHelper.clearAvailableContext();
// And clear the ViewModelStore
if (!isChangingConfigurations()) { // ***
getViewModelStore().clear(); // ***
}
}
}
});
As the starred lines show, the clear() method is called for the ViewModelStore only if the call to onDestroy() is not due to a configuration change.
Suppose we have added listener to a changeNotifier object in a view like following:
someChangeNotifierObject.addListener((){ if (this.mounted) setState(){}});
Do we need to remove the listener explicitly when the view is getting disposed?
What would be the impact if not removing it?
How to remove it since it is an inline code?
If you add a listener to a super object (an object located outside of current state) and you use setState inside of the listener - in that case you should remove it explicitly on current state dispose.
Otherwise, setState will throw an exception when the object notifies its listeners, as the state inside of which you added a listener would have been disposed to that moment.
Do not use inline functions in addListener. If you need mounted - it can be accessed anywhere throughout the State, except for static methods. Hence, simply create a new function inside of the current State class.
e.g.
#override
void initState() {
super.initState();
someChangeNotifierObject.addListener(myListenerFunc);
}
#override
void dispose() {
someChangeNotifierObject.removeListener(myListenerFunc);
super.dispose();
}
void myListenerFunc() {
print("Heya the object has changed!");
setState(() {
// re-render current stateful widget.
});
}
However, it is simply a good practice to remove listeners on dispose - no matter whether you use State's methods inside of a listener or not.
When a user clicks on a link, it uses routing to send the user to another component, you start at home and can click to charts. My problem is that I need to get the queryselector for the charts element, but when code is loaded from the component, it doesn't exist yet. How can I wait for the element to be created to execute the code?
I solved this by adding a MutationObserver inside the constructor.
Element chartsElement;
ChartsComponent() {
MutationObserver observer = MutationObserver(_onMutation);
Element my_app = querySelector('my-app');
observer.observe(my_app, childList: true);
}
_onMutation(List<dynamic> mutations, MutationObserver observer) {
mutations.forEach((value) {
MutationRecord record = value as MutationRecord;
if (record.addedNodes.contains('charts')) {
chartsElement = record.addedNodes[0];
}
});
observer.disconnect();
//Do stuff
}
Imagine, you want to listen to all clicks made to any anchor element on page. The anchors on page can be dynamically added/removed during the page lifetime and you want to register all of the click events, even on newly added.
Is there any way how to attach delegated event (like in jQuery) in Dart using its standard libraries?
In jQuery you can achieve this with element.on('click', '.selector', handler);.
You can now do that with ElementStream.matches like this :
document.body.onClick.matches('.selector').listen((Event event) {
print('Super cool!');
// The currently registered target for the event
// document.body
event.currentTarget;
// The element whose CSS selector matched
// .selector
event.matchingTarget;
// The target to which the event was originally dispatched
// the real element clicked under .selector
event.target;
});
Because I have found no viable solution, I have created package that enables delegation.
You can find it at
http://pub.dartlang.org/packages/delegate
Code is simple:
delegate(parent, condition, handler) {
return (event) {
var element = event.target;
while (element != parent && element != null) {
if (condition(element)) {
handler(event, element);
}
element = element.parent;
}
};
}
delegateOn(parent, String eventType, condition, handler) {
parent.on[eventType].listen(delegate(parent, condition, handler));
}
I have the following code:
public class FileLoader extends SwingWorker(Void, Void) {
#Override
private Void doInBackground() {
loadFiles();
}
}
public class LogInPage {
private FileLoader fileLoader = new FileLoader();
public LogInPage() {
fileLoader.execute();
}
loginButtonActionPerformed(ActionEvent evt) {
//wait for files to finish loading
//while displaying a waiting cursor
showMainForm();
}
}
My question would be:
After clicking the button, I would want all the files to be loaded first (while displaying an hourglass cursor and progress bar) before showing the main form.
I have done this before with Thread's join() but was not able to do the same with SwingWorker.
I have read about overriding done() and implementing listeners but I can't apply it here.
Any help?
Thanks.
From what you're saying and contrary to what you think, I think you can actually use SwingWorker's done() method. Before execute(), disable the button, start a busy animation, whatever, then in the done() method, do whatever it is you need to do to continue the program. That's what it's for :-)
You should also look at the SwingWorker.publish() and process() to send and receive the progress bar events.
See also: How do I wait for a SwingWorker's doInBackground() method?