flutter A build function returned null - flutter

Question

I am trying to use FutureBuilder but its showing error of A build function returned null
My code
class _EventsState extends State<Events> {
#override
Future<List> doSomeAsyncStuff() async {
final storage = new FlutterSecureStorage();
String value = await storage.read(key: 'token');
print(value);
String url = 'http://sublimeapi.netcodesolution.com/api/NewsAndEvents/';
String token = value;
final response = await http.get(url, headers: {
'Content-Type': 'application/json',
'Accept': 'application/json',
'Authorization': 'Bearer $token',
});
print('Token : ${token}');
var eventData = json.decode(response.body);
print(eventData["Data"]);
List _events = eventData["Data"];
return _events;
}
#override
Widget build(BuildContext context) {
double statusBarHeight = MediaQuery
.of(context)
.padding
.top;
return Expanded(
child: FutureBuilder(
future: doSomeAsyncStuff(),
builder: (BuildContext context, AsyncSnapshot<List> snapshot) {
List<Widget> children;
if (snapshot.connectionState == ConnectionState.done) {
if (snapshot.hasData) {
print('working');
print(snapshot.data);
return Container(
child: Column(
children: <Widget>[
Text('working')
],
),
);
}
}
}),
);
}
As you can see in code I am fetching data from API and its working fine. In code i print the value of _events in setState its also printing the value like this
I/flutter (32627): [{Id: 38, Description: Two days Workshop on Prevention of Suicide organized for GPs of Thar., ImagePath: /journals/2e8a55f3-6612-4b23-a0ea-e91022c159a8.pdf, CreatedBy: 4447, CreatedOn: 2019-09-18T14:56:13.357, Active: false, Type: Events, Attachment: null, AttachmentType: Events}
I need to print the Description value of this data in future widget but don't know why its showing error

Answer 1

The Error says it clearly! It returned null.
So you have to return something! Do something like this,
Future<List> doSomeAsyncStuff() async {
final storage = new FlutterSecureStorage();
String value = await storage.read(key: 'token');
print(value);
String url = 'http://sublimeapi.netcodesolution.com/api/NewsAndEvents/';
String token = value;
final response = await http.get(url, headers: {
'Content-Type': 'application/json',
'Accept': 'application/json',
'Authorization': 'Bearer $token',
});
print('Token : ${token}');
var eventData = json.decode(response.body);
print(eventData["Data"]);
List _events = eventData["Data"];
return _events;
}
and also, we missed another case here.
Scaffold(
appbar: AppBar(
title: const Text('Sample Future Builder'),
),
body: Expanded(
child: FutureBuilder(
future: doSomeAsyncStuff(),
builder: (BuildContext context, AsyncSnapshot<List> snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
if (snapshot.hasData) {
print('working');
print(snapshot.data);
return Container(
child: Column(
children: <Widget>[
Text('working')
],
),
);
}
}
return Center(child: Text("Not Loaded Yet!!"),)
}
),
),
);
Hope that solves your issue!
Tip: Move all your widgets under Scaffold. It would be the best practice. Refer this