Flutter Provider doesn't rebuild widget

Question

here's a piece of my code, but please read the question before jumping to conclusions:

class RescheduleCard extends StatelessWidget {

@override
  Widget build(BuildContext context)=> Consumer<AppSnapshot>(
    builder: (context, appSnapshot, _)=>
    (appSnapshot.reschedule!=null)
    ?RescheduleBuilder(
          model: appSnapshot.reschedule,
          controllers: appSnapshot.controllers,
        )
    :Carouselcard(
      title:  carouselPageTitle(title: rescheduleTitle,test: appSnapshot.test),
      colors: yellows,

so I'm sort of new to provider and I'm used to Bloc, my api once receive some call the provider and set a model;

edit: here's the provider 256 lines tripped down to what concern the "reschedule"...

class AppSnapshot with ChangeNotifier {

  RescheduleModel _reschedule;
  RescheduleModel get reschedule => _reschedule;

  void cleanReschedule() {
    reschedule=null;
    notifyListeners();
  }

  set reschedule(RescheduleModel reschedule) {
    _reschedule=reschedule;
    notifyListeners();
  }
}

re-edit: on top of everything:

void main() async {
  final AppSnapshot _appSnapshot = AppSnapshot();
  await _appSnapshot.load();
  runApp(ChangeNotifierProvider(
          builder: (context) => _appSnapshot,
          child: Initializer()));
}

I'm expecting the "Consumer" to rebuild my widget, but doesn't!

I'm sure the data is there, because the widget is inside a carousel and as soon as I move it it rebuilds properly.

what am I missing? thank you

re-re-edit: here's an example of another Carousel Card where provider works quilckly and changes apply in realtime

 Consumer<AppSnapshot>(
    builder: (context, appSnapshot, _)=> Carouselcard(
      title: carouselPageTitle(title: optionsTitle,test: appSnapshot.test),
      colors: lightBlues,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          ((appSnapshot.id??'')!='')                                                        // ID WIDGET
            ? ListTile(
              leading: CustomIcon(
                icon: deleteIcon,
                onTap: () => appSnapshot.deleteID(),
              ),
              title: _customCard(onTap:()=> _showID(id: appSnapshot.id,context: context)),
              subtitle: Text(tap2delete,textScaleFactor:0.8),
            )
            : IdTile(),

for the man himself, of course :) I stripped down the provider to what is related to the object otherwise it would be a lot of code... note that in other widgets the provider works as intended, even here it passes the data, just doesn't rebuilds until otherwise refreshed — Francesco Iapicca, Jul 31 '19 at 14:21
I was more thinking about `ChangeNotifierProvider`. Similarly, are you *sure* that the `builder` method isn't called again? If you add a log there, it's not reached? — Rémi Rousselet, Jul 31 '19 at 14:33
post updated... but hold on... I can "consume" more than once, can I? — Francesco Iapicca, Jul 31 '19 at 14:36
You sure can. Is here another provider of an object of the type `AppSnapshot` ? — Rémi Rousselet, Jul 31 '19 at 14:39
a lot of them.... there are many object in it and some business logic, I posted a working one, I don't see much difference to be hones :/ — Francesco Iapicca, Jul 31 '19 at 14:44
I don't mean other consumers, but other providers. Do you have only one provider for this kind of object? — Rémi Rousselet, Jul 31 '19 at 14:52
crap, I need to go. I'll do that tomorrow, I'll make some logging and see if I can find some clue... thanks for the help @RémiRousselet — Francesco Iapicca, Jul 31 '19 at 15:00

Brian Ogden · Accepted Answer · 2020-04-06T04:05:09.803

2

According to this article the FutureProvider does not listen for changes, it will only rebuild Consumers 1 time, when Future is complete.

The article even explains how the author tested this.

The developer of the Dart Provider package also explains the use case for FutureProvider.

edited Apr 06 '20 at 04:05

answered Apr 06 '20 at 03:48

Brian Ogden

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score 0 · Answer 2 · answered Dec 18 '19 at 12:33

0

Specificies the type in main.dart

void main() async {
final AppSnapshot _appSnapshot = AppSnapshot();
await _appSnapshot.load();
runApp(ChangeNotifierProvider< **AppSnapshot** >(
      builder: (context) => _appSnapshot,
      child: Initializer()));
}

answered Dec 18 '19 at 12:33

AlexPad

10,364
3
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48

Why do you think this would have any effect? – Brian Ogden Apr 06 '20 at 03:48

Flutter Provider doesn't rebuild widget

2 Answers2