single document in same collection Firestore Flutter - flutter

Question

I build a quiz app and i use firestore for the data, i need a code for this : when the user select answer 1 he goes to page A , but when he select answer 2 he goes to page B ... etc
This is where am i : all the answers go to the same page when i tap on it, i want for every answer has his own page
This is my code :
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
class question14 extends StatefulWidget {
#override
_question14State createState() => _question14State();
}
class _question14State extends State<question14> {
int selectedIndex
#override
Widget build(BuildContext context) {
return Scaffold(
body: StreamBuilder(
stream: Firestore.instance.collection('numberzz').snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) return const Text('Loading ...');
return ListView.builder(
scrollDirection: Axis.horizontal,
padding: EdgeInsets.fromLTRB(100.0, 0.0, 0.0, 0.0),
itemExtent: 200.0,
itemCount: snapshot.data.documents.length,
itemBuilder: (BuildContext context, int index) {
final DocumentSnapshot document =
snapshot.data.documents[index];
return Container(
padding: EdgeInsets.fromLTRB(0.0, 300.0, 0.0, 450.0),
child: ListTile(
contentPadding: selectedIndex == index
? EdgeInsets.all(0.0)
: EdgeInsets.all(25.0),
title: Image.network(
document['number'],
),
selected: selectedIndex == index,
onTap: () {
Firestore.instance.runTransaction((transaction) async {
DocumentSnapshot freshSnap =
await transaction.get(document.reference);
await transaction.update(freshSnap.reference, {
'vote': freshSnap['vote'] + 1,
});
});
Navigator.push(
context, MaterialPageRoute(
builder: (context) => new page()));
setState(() {
selectedIndex = index;
});
},
),
);
},
);
}));
}
}
thanks for your help !

Answer 1

You can check which index is selected before navigating. Kind of conditional navigation.
switch(selectedIndex){
case 0:
Navigator.of(context).push(.....(Page A));
break;
case 1:
.......
break;
I think you get the point.
But this code should come after
setState(() { selectedIndex = index };