ChipSelect callback is not updating the UI. Flutter - flutter

Question

I gave up trying to find the reason setState() is not running build method. I have a ChoiceChip which has a callback function. Debug showed me that I actually receive the selected chip at the callback but setState() is not updating the ui. I have spent all day trying to understand why setState() is not running the build() method. Here is my code
class SocialStoryCategory extends StatefulWidget {
final Function(String) onMenuItemPress;
SocialStoryCategory({Key key, #required this.onMenuItemPress}) : sup er(key: key);
#override
_SocialStoryCategoryState createState() => _SocialStoryCategoryState();
}
class _SocialStoryCategoryState extends State<SocialStoryCategory> {
int _value = 0;
List<String> categoryList;
#override
Widget build(BuildContext context) {
categoryList = [
NoomeeLocalizations.of(context).trans('All'),
NoomeeLocalizations.of(context).trans('Communication'),
NoomeeLocalizations.of(context).trans('Behavioral'),
NoomeeLocalizations.of(context).trans('ADL'),
NoomeeLocalizations.of(context).trans('Other')
];
return Wrap(
spacing: 4,
children: List<Widget>.generate(5, (int index) {
return Theme(
data: ThemeData.from(
colorScheme: ColorScheme.light(primary: Colors.white)),
child: Container(
child: ChoiceChip(
elevation: 3,
selectedColor: Colors.lightBlueAccent,
label: Text(categoryList.elementAt(index)),
selected: _value == index,
onSelected: (bool selected) {
setState(() {
_value = selected ? index : null;
if (categoryList.elementAt(_value) == "All") {
widget.onMenuItemPress("");
} else {
widget.onMenuItemPress(categoryList.elementAt(_value));
}
});
},
),
),
);
}).toList());
}
}
Here is the place where I get the callback
class SocialStoriesHome extends StatefulWidget {
#override
_SocialStoriesHomeState createState() => _SocialStoriesHomeState();
}
class _SocialStoriesHomeState extends State<SocialStoriesHome>
with TickerProviderStateMixin {
String title;
TabController _tabController;
int _activeTabIndex = 0;
String _defaultStoryCategory;
_goToDetailsPage() {
Navigator.of(context).pushNamed("parent/storyDetails");
}
#override
void dispose() {
_tabController.dispose();
super.dispose();
}
#override
void initState() {
super.initState();
_tabController = TabController(vsync: this, length: 2);
_defaultStoryCategory = '';
}
#override
Widget build(BuildContext context) {
return BaseWidget<SocialStoryViewModel>(
model: new SocialStoryViewModel(
socialStoriesService: Provider.of(context),
),
onModelReady: (model) =>
model.fetchDefaultStoriesByCategory(_defaultStoryCategory),
builder: (context, model, child) => DefaultTabController(
length: 2,
child: Scaffold(
body: model.busy
? Center(child: CircularProgressIndicator())
: Container(
child: Column(
children: <Widget>[
new SocialStoryCategory(
onMenuItemPress: (selection) {
setState(() {
_defaultStoryCategory = selection;
});
},
),
Expanded(
child: ListView(
children: getStories(model.socialStories),
),
),
],
),
),
);
}
}
List<Widget> getStories(List<SocialStoryModel> storyList) {
List<Widget> list = List<Widget>();
for (int i = 0; i < storyList.length; i++) {
list.add(Padding(
padding: const EdgeInsets.all(8.0),
child: Template(
title: storyList[i].name,
subTitle: storyList[i].categories,
hadEditIcon: false),
));
}
return list;
}

Answer 1

Finally I have found the solution.
I have simply replaced
new SocialStoryCategory(onMenuItemPress: (selection) {
setState(() {
_defaultStoryCategory = selection;
});
},
),
to
new SocialStoryCategory(
onMenuItemPress: (selection) {
model.fetchDefaultStoriesByCategory(selection);
},
),
my viewModel extend change notifier and build a child as consumer so I totally understand why it works. But I still do not understand why the previous version was not working. I will feel happy again only when you explain me the problem,