Can't get data from api - flutter

Question

While I am passing value from home page in API page after applying logic how I am not getting data in my result variable. What I am doing wrong?
Here is my home page where I passes the value -
import 'package:flutter/material.dart';
import 'sourceScreen.dart';
import 'models/API.dart';
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
int value=0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title:Text("uTTerNews")),
body: Center(
child: Column(
children: <Widget>[
FlatButton(
onPressed: (){
Navigator.push(context, MaterialPageRoute(builder: (context)=>SourceScreen({})));
setState(() {
value =1;
API(value: value);
});
},
child:Text('India'),
color: Colors.blue,
),
FlatButton(
onPressed: (){
Navigator.push(context, MaterialPageRoute(builder: (context)=>SourceScreen({})));
setState(() {
value =0;
API(value: value);
});
},
child:Text('World'),
color: Colors.blue,
),
],
),
),
);
}
}
Here is my API page where I wanna use that value with some logic which is given below hope u will understand-
import 'model.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
class API{
int value;
API({this.value});
Future<List<Source>> fetchNewsSource() async {
final world ='https://newsapi.org/v2/sources?apiKey=';
final india = 'https://newsapi.org/v2/sources?language=en&country=in&apiKey=';
String result;
void logic(){
if(value==1){
result = india;
}
else if(value==0){
result = world;
}
}
final response = await http.get(result);
if (response.statusCode == 200) {
List sources = json.decode(response.body)['sources'];
return sources.map((source) => new Source.formJson(source)).toList();
} else {
throw Exception('Fail to load data');
}
}
}
Here is home page -
import 'package:flutter/material.dart';
import 'sourceScreen.dart';
import 'models/API.dart';
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
int value=0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title:Text("uTTerNews")),
body: Center(
child: Column(
children: <Widget>[
FlatButton(
onPressed: (){
Navigator.push(context, MaterialPageRoute(builder: (context)=>SourceScreen({})));
setState(() {
value =1;
API(value: value);
});
},
child:Text('India'),
color: Colors.blue,
),
FlatButton(
onPressed: (){
Navigator.push(context, MaterialPageRoute(builder: (context)=>SourceScreen({})));
setState(() {
value =0;
API(value: value);
});
},
child:Text('World'),
color: Colors.blue,
),
],
),
),
);
}
}
Source screen
import 'package:flutter/material.dart';
import 'models/model.dart';
import 'models/card.dart';
import 'article.dart';
import 'models/API.dart';
class SourceScreen extends StatefulWidget {
SourceScreen(Map<int, int> map);
#override
_SourceScreenState createState() => _SourceScreenState();
}
class _SourceScreenState extends State<SourceScreen> {
var list_source;
var refreshKey = GlobalKey<RefreshIndicatorState>();
#override
void initState() {
super.initState();
refreshListSource();
}
Future<Null> refreshListSource() async {
API api = new API();
refreshKey.currentState?.show(atTop: false);
setState(() {
list_source = api.fetchNewsSource();
});
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
backgroundColor: Color.fromRGBO(58, 66, 86, 1.0),
appBar: AppBar(
elevation: 1.0,
backgroundColor: Color.fromRGBO(58, 66, 86, 1.0),
title: Text('uTTerNews'),
),
body: Center(
child: RefreshIndicator(
child: FutureBuilder<List<Source>>(
future: list_source,
builder: (context, snapshot) {
if (snapshot.hasError) {
Text('Error: ${snapshot.error}');
} else if (snapshot.hasData) {
List<Source> sources = snapshot.data;
return new ListView(
children: sources
.map((source) =>
GestureDetector(
onTap: () {
Navigator.push(context, MaterialPageRoute(
builder: (context) =>
articleScreen(source: source,)));
},
child: card(source),
))
.toList());
}
return CircularProgressIndicator();
},
),
onRefresh: refreshListSource),
),
),
);
}
}

Answer 1

Output:
Try this full code:
void main() => runApp(MaterialApp(home: Home()));
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
int value = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("uTTerNews")),
body: Center(
child: Column(
children: <Widget>[
FlatButton(
onPressed: () async {
value = 1;
List list = await API(value: value).fetchNewsSource();
Navigator.push(context, MaterialPageRoute(builder: (context) => SourceScreen(list)));
},
child: Text('India'),
color: Colors.blue,
),
FlatButton(
onPressed: () async {
value = 0;
List list = await API(value: value).fetchNewsSource();
Navigator.push(context, MaterialPageRoute(builder: (context) => SourceScreen(list)));
},
child: Text('World'),
color: Colors.blue,
),
],
),
),
);
}
}
class API {
int value;
API({#required this.value});
Future<List<dynamic>> fetchNewsSource() async {
final world = 'https://newsapi.org/v2/sources?apiKey=$apiKey';
final india = 'https://newsapi.org/v2/sources?language=en&country=in&apiKey=$apiKey';
String result;
if (value == 1)
result = india;
else if (value == 0) result = world;
final response = await http.get(result);
if (response.statusCode == 200) {
List sources = json.decode(response.body)['sources'];
return sources;
} else {
throw Exception('Fail to load data');
}
}
}
class SourceScreen extends StatefulWidget {
final List list;
SourceScreen(this.list);
#override
_SourceScreenState createState() => _SourceScreenState();
}
class _SourceScreenState extends State<SourceScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Channels")),
body: ListView(
children: widget.list.map((map) => ListTile(title: Text(map["name"]))).toList(),
),
);
}
}