Flutter send and show data between BottomNavigationBarItem - flutter

Question

I want to share and show data between BottomNavigationBarItems
It is my BottomNavigationBar page:
class BottomNavigationBarController extends StatefulWidget {
#override
_BottomNavigationBarControllerState createState() =>
_BottomNavigationBarControllerState();
}
class _BottomNavigationBarControllerState
extends State<BottomNavigationBarController> {
List<Widget> pages = [];
#override
void initState() {
pages.add(HomePage(
key: PageStorageKey('HomePage'),
));
pages.add(MapPage(
key: PageStorageKey('MapPage'),
));
super.initState();
}
int _currentIndex = 0;
Widget _bottomNavigationBar(int selectedIndex) => BottomNavigationBar(
onTap: (int index) => setState(() => _currentIndex = index),
currentIndex: selectedIndex,
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(icon: Icon(Icons.home), label: "Home"),
BottomNavigationBarItem(icon: Icon(Icons.map), label: "MapPage"),
],
);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("iArrived"),
actions: _currentIndex != 1
? <Widget>[
IconButton(
icon: Icon(Icons.keyboard_arrow_right),
onPressed: () {
setState(() {
_currentIndex++;
});
})
]
: null),
backgroundColor: Colors.white,
bottomNavigationBar: _bottomNavigationBar(_currentIndex),
body: IndexedStack(
index: _currentIndex,
children: pages,
),
);
}
}
And I want to send my location from the MapPage to the HomePage.
There is a function in the MapPage that is executed when the place change:
void _setLocation(LatLng latlng) {
setState(() {
lat = latlng.latitude;
lng = latlng.longitude;
});
}
I think I have to call some function like a callback inside _setLocation() but I don't know how to implement it to show the location on my HomePage and have it refresh every time I change it.
Thanks for the help.
If your answer is to use shared_preferences plugin, can you tell me how would you implement it? Because I tried it and it did not work for me.
Thanks again.

Answer 1

You can use provider plugin for state management:
Create a model that store a shared value:
class LocationModel extends ChangeNotifier {
Location location;
void updateLocation(Location location) {
this.location = location;
notifyListeners();
}
}
Wrap your root widget with Provider class:
#override
Widget build(BuildContext build) {
return ChangeNotifierProvider(
create: (_) => LocationModel(),
child: App(),
);
}
When you changing a shared value in a model (you need to get a model from Provider, it depends on concrete implementation). For example:
onTap() {
model.updateLocation(newLocation):
}