This question already has answers here:
Flutter: Run method on Widget build complete
(14 answers)
Closed 3 years ago.
The problem is, I need to call method after widget is built, otherwise I'm getting an error.
So I want to know is there a way to check whether widget is built, maybe a listener?
All widgets have a bool this.mounted property. It turns true when the buildContext is assigned.
Tip: Its a good practice to set the state of any widget only after the widget is built and I usually use this bool to set states once it is true. It is an error to call setState when a widget is unmounted or before it is mounted.
In your case, I feel you need the same thing, run your method if this.mounted == true.
Related
Flutter: how get all properties for all widgets's objects in my flutter app by dart Code to use it in Automated Testing ?
I know exist three types from testing :
1. Unit tests.
2. Widget tests.
3. Integration tests.
But I just want to know all the details about each Widget and also Write it in a text file?
for Example this image explain an example in Dev tool But I neet it by codeing
Thanks in advance
In your tests you could use this code to access the properties of a widget in the current tree:
final FloatingActionButton fab = tester.widget(find.byType(FloatingActionButton));
expect(fab.tooltip, ...);
Here you tell the WidgetTester to find a widget in the current widget tree, when a widget is found you can access its properties.
Important, that your 'First A, Arrange' is correctly setup, thus a widget tree is build and the widget you're looking for is available.
When you are searching for a more generic widget which occures more then once in the widget tree I suggest using the find.byKey method, like so:
tester.widget(find.byKey(Key('exampleKey')));
Ofcourse, the Finder widget has more than two methods, thus any of the other find methods could be used.
Greetz
I am trying to deep dive into inherited widget and got stuck somewhere. When i debug on updateShouldNotify method, its parameter(old widget) has same data with the new one. Also the instances are same. Due to that contition always false and my dependent widgets dont rebuild.
I put my simple code on dartpad. Can you spot the problem that i am doing?
just push the increase from profile
https://dartpad.dev/b6409e10de32b280b8938aa75364fa7b
Thanks
I know that any dependency change will rebuild a widget after firing didChangeDependencies.
Is there a way of preventing the Widget from rebuilding?
I can see that didChangeDependencies returns void when maybe if should return a boolean in order to cancel a rebuild?
But is there another way of stopping the widget rebuilding?
(yes I know, the smart answer will be - "if it's a dependency then it should build, otherwise it's not a dependency", but just humour/humor me ok )
Maybe the updateShouldNotifyDependent method is what you want
This question already has answers here:
Flutter: Run method on Widget build complete
(14 answers)
Closed 3 years ago.
Beginner question:
I'm trying to display a message as soon as the page display, I can do it with a simple custom message, but I couldn't find any standard way to do it, all search I did leads me to Snackbar or Flushbar, the problem with this 2 is that u can only show it after the build is called, e.g. on onPress, which leads me to the actual question:
How do I get a call back for onMount event, e.g. something like jQuery ready method, that is triggered once the page is mounted (i.e. ready), so that I can call Snackbar for example?
Duplicate to Flutter: Run method on Widget build complete
answer:
#override
void initState() {
super.initState();
if (SchedulerBinding.instance.schedulerPhase ==
SchedulerPhase.persistentCallbacks) {
SchedulerBinding.instance.addPostFrameCallback((_) {
showInFlushbar("Some text");
});
}
;
}
Here is my problem: I have an app that has 2 list view.builders. You can imagine the scenario.
within the Stateful widget, we have:
Widget build(ct)
{
and this returns a column widget that has TWO list views.
The problem I have is that one list view changes (or should change) the items in another list view.
So what are my options? To create two Widget build(ct1) and Widget build(ct2)??
Do we do that? How can I communicate changes to ct1?
Oh my goodness, I've tried a lot, even setState etc... nothing works.. Perhaps could someone tell me how I can invoke the page to be refreshed?? That would work.
I keep on finding the answers myself - but for anyone who has this issue, Flutter apparently has evolved... if you are using the latest version, I really believe that SetState() function should work for you.. you just need to use it in the right place.