How to update state from static method in Flutter? - flutter

Question

I have a bottom nav bar that uses this code to switch widgets:
void _onItemTapped(int index) {
setState(() {
selectedIndexGlobal = index;
print(index);
});
}
And shows the needed widgets in body:
body: SafeArea(
child: new LayoutBuilder(
builder: (BuildContext context, BoxConstraints constraints) {
Container con = Container(
child: _widgetOptions.elementAt(selectedIndexGlobal)
);
return con;
}
))
I also have a GridView with static children list loaded from Firebase, and tried to apply a GestureDetector to it, to change selectedIndex and update screen state:
static getExpenseItems(AsyncSnapshot<QuerySnapshot> snapshot, BuildContext context) {
try {
snapshot.data.documents.sort((a, b) =>
a.data["order"].compareTo(b.data["order"]));
} on NoSuchMethodError {}
return snapshot.data.documents
.map((doc) =>
new GestureDetector(
behavior: HitTestBehavior.translucent,
onTap: () {
catName = doc["catName"];
setState(() {
selectedIndexGlobal = 4;
});
},
child: new Container(
child: Container(
padding: EdgeInsets.only(top: 15, left: 10, bottom: 15),
decoration: new BoxDecoration(
border: new Border.all(color: Colors.grey[200],
width: 0.8)),
child: Align(
alignment: Alignment.centerLeft,
child: Text(doc["name"],
style: TextStyle(fontSize: categoriesFont),
textAlign: TextAlign.center),
)
)
)
)
).toList();
}
But setState can't be called from a static method, as well as GridView.count doesn't let me use non-static widgets as child. What should I do then to update state on click?

Answer 1

This line will help you get the instance of the Widget State object you need.
All you need access to is the current context object:
_HomeState stateObject = context.findAncestorStateOfType<_HomeState>();
stateObject.setState(() {
_tabIndex = index;
});
For this to work, ensure that the context you use to access the State Object is from a child widget of the State object you are trying to find.