Flutter variable keeps getting initialized after switching to the class - flutter

Question

I am trying to apply filters in firebase and am doing so by using startswith filters in the results.I have initialized the variables which act as a filter outside of all the classes
int duration = 1440;
String destination = '';
String Company = '';
int Maxcost = 99999999999;
int MinCost = 0;
String cla = '';
String airport = '';
This means that all files will be allowed to come. But when I change the variables from another class like this.
FILTER CLASS
Navigator.pushReplacement(
context, MaterialPageRoute(builder: (context) => Home(email:email,destination:destination,duration:duration,Maxcost: maxCost,Mincost: minCost,airport: airport,Company: company,)));
RECIEVING CLASS(Stateful Widget)
Home({this.email,duration = 1440,destination ='',Company = '',Maxcost = 99999999,Mincost = 0,cla = '',airport = ''});
I have added "=" as there are other classes which lead to this but they don't give these values. This makes it so that when those classes don't pass these values, it becomes the default values instead of null. Now where the problem occurs
StreamBuilder(
stream: Firestore.instance.collection("Planes").where(
"cost", isLessThan: Maxcost).where(
"cost", isGreaterThan: MinCost).snapshots(),
builder: (context, snapshot) {
List<DocumentSnapshot> m = snapshot.data.documents;
List<DocumentSnapshot> l=[];
DocumentSnapshot i;
for (i in m) {
if (i[' destination'].startsWith(destination) && i['duration']<(duration) && i['airport'].startsWith(airport) && i['class'].startsWith(cla) && i['company'].startsWith(Company)) {
l.add(i);
}
}
return ListView.builder(
itemCount: l.length,
itemBuilder: (context, index) {
return Padding(
padding: const EdgeInsets.symmetric(
vertical: 1.0, horizontal: 4.0),
child: Card(
child: ListTile(
onTap: () {
Navigator.push(context, MaterialPageRoute(
builder: (context) =>
ViewPlane(plane: snapshot,
index: index,
email: email,)));
},
leading: Icon(Icons.airplanemode_active),
title: Text(l[index][' destination']),
subtitle: Text(
l[index]['airport']),
),
),
);
},
);
}
),
Before this happens(It is one of the first things done), the variable is set to the default values. How come? The variables are not initialized in the build function. Here is the entire code for the main class if needed.
MAIN CLASS
import 'dart:io';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:discount_app/AddSheets/AddPlane.dart';
import 'package:discount_app/FilterPage/PlaneFilter.dart';
import 'package:discount_app/Headings/home_screen_plane_packages.dart';
import 'package:discount_app/chat_pack/Loading.dart';
import 'package:discount_app/chat_pack/Settings.dart';
import 'package:discount_app/chat_pack/chat_home_page.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:discount_app/ViewSheets/ViewPlane.dart';
import 'package:discount_app/login_signup/Login.dart';
import 'package:discount_app/chat_pack/Const.dart';
import 'package:google_sign_in/google_sign_in.dart';
List<Choice> choices = const <Choice>[
const Choice(title:"Filters",icon:Icons.filter),
const Choice(title: 'Settings', icon: Icons.settings),
const Choice(title: 'Log out', icon: Icons.exit_to_app),
];
int duration = 1440;
String destination = '';
String Company = '';
int Maxcost = 99999999999;
int MinCost = 0;
String cla = '';
String airport = '';
#override
class Home extends StatefulWidget {
String email;
Home({this.email,duration = 1440,destination ='',Company = '',Maxcost = 99999999,Mincost = 0,cla = '',airport = ''});
#override
_HomeState createState() => _HomeState(email:email);
}
class _HomeState extends State<Home> {
var s;
void onItemMenuPress(Choice choice,) {
if (choice.title == 'Log out') {
handleSignOut();
}
else if (choice.title == 'Filters') {
Navigator.push(
context, MaterialPageRoute(builder: (context) => planeFilter(email:email)));
}
else {
Navigator.push(
context, MaterialPageRoute(builder: (context) => Settings()));
}
}
final GoogleSignIn googleSignIn = GoogleSignIn();
bool isLoading = false;
Future<Null> openDialog() async {
switch (await showDialog(
context: context,
builder: (BuildContext context) {
return SimpleDialog(
contentPadding: EdgeInsets.only(
left: 0.0, right: 0.0, top: 0.0, bottom: 0.0),
children: <Widget>[
Container(
color: themeColor,
margin: EdgeInsets.all(0.0),
padding: EdgeInsets.only(bottom: 10.0, top: 10.0),
height: 100.0,
child: Column(
children: <Widget>[
Container(
child: Icon(
Icons.exit_to_app,
size: 30.0,
color: Colors.white,
),
margin: EdgeInsets.only(bottom: 10.0),
),
Text(
'Exit app',
style: TextStyle(color: Colors.white,
fontSize: 18.0,
fontWeight: FontWeight.bold),
),
Text(
'Are you sure to exit app?',
style: TextStyle(color: Colors.white70, fontSize: 14.0),
),
],
),
),
SimpleDialogOption(
onPressed: () {
Navigator.pop(context, 0);
},
child: Row(
children: <Widget>[
Container(
child: Icon(
Icons.cancel,
color: primaryColor,
),
margin: EdgeInsets.only(right: 10.0),
),
Text(
'CANCEL',
style: TextStyle(
color: primaryColor, fontWeight: FontWeight.bold),
)
],
),
),
SimpleDialogOption(
onPressed: () {
Navigator.pop(context, 1);
},
child: Row(
children: <Widget>[
Container(
child: Icon(
Icons.check_circle,
color: primaryColor,
),
margin: EdgeInsets.only(right: 10.0),
),
Text(
'YES',
style: TextStyle(
color: primaryColor, fontWeight: FontWeight.bold),
)
],
),
),
],
);
})) {
case 0:
break;
case 1:
exit(0);
break;
}
}
Future<Null> handleSignOut() async {
this.setState(() {
isLoading = true;
});
await FirebaseAuth.instance.signOut();
await googleSignIn.disconnect();
await googleSignIn.signOut();
this.setState(() {
isLoading = false;
});
Navigator.of(context)
.pushAndRemoveUntil(
MaterialPageRoute(builder: (context) => LoginScreen()), (
Route<dynamic> route) => false);
}
String email;
_HomeState({this.email});
#override
Widget build(BuildContext context) {
return GestureDetector(
onPanUpdate: (details) {
if (details.delta.dx > 0) {
Navigator.pushReplacement(context, MaterialPageRoute(
builder: (context) => PlanePackages(email: email,)));
}
},
child: new Scaffold(
backgroundColor: Colors.pink[800],
appBar: new AppBar(
title: new Text('Home page'),
actions: <Widget>[
Padding(
padding: EdgeInsets.only(right: 20.0),
child: GestureDetector(
onTap: () {
Navigator.push(context, MaterialPageRoute(
builder: (context) =>
HomeScreen(currentUserId: email,)));
},
child: Icon(Icons.chat),
)),
PopupMenuButton<Choice>(
onSelected: onItemMenuPress,
itemBuilder: (BuildContext context) {
return choices.map((Choice choice) {
return PopupMenuItem<Choice>(
value: choice,
child: Row(
children: <Widget>[
Icon(
choice.icon,
color: primaryColor,
),
Container(
width: 10.0,
),
Text(
choice.title,
style: TextStyle(color: primaryColor),
),
],
));
}).toList();
},
),
],
),
body: WillPopScope(
child: Stack(
children: <Widget>[ StreamBuilder(
stream: Firestore.instance.collection("Planes").where(
"cost", isLessThan: Maxcost).where(
"cost", isGreaterThan: MinCost).snapshots(),
builder: (context, snapshot) {
List<DocumentSnapshot> m = snapshot.data.documents;
List<DocumentSnapshot> l=[];
DocumentSnapshot i;
for (i in m) {
if (i[' destination'].startsWith(destination) && i['duration']<(duration) && i['airport'].startsWith(airport) && i['class'].startsWith(cla) && i['company'].startsWith(Company)) {
l.add(i);
}
}
return ListView.builder(
itemCount: l.length,
itemBuilder: (context, index) {
return Padding(
padding: const EdgeInsets.symmetric(
vertical: 1.0, horizontal: 4.0),
child: Card(
child: ListTile(
onTap: () {
Navigator.push(context, MaterialPageRoute(
builder: (context) =>
ViewPlane(plane: snapshot,
index: index,
email: email,)));
},
leading: Icon(Icons.airplanemode_active),
title: Text(l[index][' destination']),
subtitle: Text(
l[index]['airport']),
),
),
);
},
);
}
),
Positioned(
child: isLoading ? const Loading() : Container(),
)
]
),
onWillPop: () async {
openDialog();
return Future.value(false);
},
),
floatingActionButton: FloatingActionButton(
onPressed: () {
print(cla);
Navigator.push(context, MaterialPageRoute(
builder: (context) => AddPlane(email: email,)));
},
backgroundColor: Colors.green,
child: Icon(
Icons.add,
size: 30,
),
),
),
);
}
}
Any help will be appreciated

Answer 1

Navigator.pushReplacement(
context, MaterialPageRoute(builder: (context) => Home(email:email,destationName:destination,durationValue:duration,maximumCost: maxCost,minimumCost: minCost,airportName: airport,CompanyName: company,)));
assign it this way, since they're global variables you can't assign directly in the constructor parameters
Home({this.email,durationValue = 1440,destinationName ='',companyName = '',maximumCost = 99999999,minimumCost = 0,claValue = '',airportName = ''})
{
duration=durationValue;
destination=destinationName;
Maxcost = maximumCost;
Mincost = minimmCost;
cla=claValue;
airport=airportName;
Company = companyName;
}