Flutter avoid multiple running FutureBuilder - flutter

Question

in my simple code as new screen, unfortunately FutureBuilder work and get data from method twice!!
i'm not sure whats problem and how can i avoid that
class LessonDetail extends StatefulWidget {
final String monthKey;
final String lessonFileKey;
LessonDetail({#required this.monthKey, #required this.lessonFileKey});
#override
State<StatefulWidget> createState() {
return _LessonDetailState(monthKey, lessonFileKey);
}
}
class _LessonDetailState extends BaseState<LessonDetail> {
String monthKey;
String lessonFileKey;
_LessonDetailState(this.monthKey, this.lessonFileKey);
#override
Widget build(BuildContext context) {
return Directionality(
textDirection: TextDirection.rtl,
child: Scaffold(
body: FutureBuilder(
future: _getLessonDetail(),
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
PlayLessonResponse response = snapshot.data;
print(response);
}
return Center(
child: CircularProgressIndicator(),
);
}),
),
);
}
Future<PlayLessonResponse> _getLessonDetail() async {
AudioList audioList = AudioList(
'http://www.sample.com',
'aaaaa'
);
List<AudioList> lst = [audioList,audioList,audioList];
PlayLessonResponse response = PlayLessonResponse(
2,
'',
'http://www.sample.com',
'2',
lst,
1,
'ssss'
);
print('++++++++++++++++++++');
return response;
}
}
BaseState class content:
abstract class BaseState<T extends StatefulWidget> extends State {
final Connectivity _connectivity = Connectivity();
StreamSubscription<ConnectivityResult> _connectivitySubscription;
bool isOnline = true;
Future<void> initConnectivity() async {
try {
await _connectivity.checkConnectivity();
} on PlatformException catch (e) {
print(e.toString());
}
if (!mounted) {
return;
}
await _updateConnectionStatus().then((bool isConnected){
if(mounted){
setState(() {
isOnline = isConnected;
});
}
});
}
#override
void initState() {
super.initState();
initConnectivity();
_connectivitySubscription = Connectivity()
.onConnectivityChanged
.listen((ConnectivityResult result) async {
await _updateConnectionStatus().then((bool isConnected){
if(mounted){
setState(() {
isOnline = isConnected;
});
}
});
});
}
#override
void dispose() {
_connectivitySubscription.cancel();
super.dispose();
}
Future<bool> _updateConnectionStatus() async {
bool isConnected;
try {
final List<InternetAddress> result =
await InternetAddress.lookup('google.com');
if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
isConnected = true;
}
} on SocketException catch (_) {
isConnected = false;
return false;
}
return isConnected;
}
}
output:
I/flutter (32289): ++++++++++++++++++++
I/flutter (32289): ++++++++++++++++++++

Answer 1

Just like what #Ricardo said, you shouldn't call the function directly inside the FutureBuilder's future method.
Instead, you should 1st run your function in init state, and store the response in a new variable. Only then assign variable to the future of FutureBuilder.
Code Example:
class LessonDetail extends StatefulWidget {
final String monthKey;
final String lessonFileKey;
LessonDetail({#required this.monthKey, #required this.lessonFileKey});
#override
State<StatefulWidget> createState() {
return _LessonDetailState(monthKey, lessonFileKey);
}
}
class _LessonDetailState extends BaseState<LessonDetail> {
String monthKey;
String lessonFileKey;
Future<PlayLesssonResponse> _myResponse; //added this line
_LessonDetailState(this.monthKey, this.lessonFileKey);
#override
void initState() {
_myResponse = _getLessonDetail(); // added this line
super.initState();
}
#override
Widget build(BuildContext context) {
return Directionality(
textDirection: TextDirection.rtl,
child: Scaffold(
body: FutureBuilder(
future: _myResponse, //use _myResponse variable here
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
PlayLessonResponse response = snapshot.data;
print(response);
}
return Center(
child: CircularProgressIndicator(),
);
}),
),
);
}
Future<PlayLessonResponse> _getLessonDetail() async {
AudioList audioList = AudioList(
'http://www.sample.com',
'aaaaa'
);
List<AudioList> lst = [audioList,audioList,audioList];
PlayLessonResponse response = PlayLessonResponse(
2,
'',
'http://www.sample.com',
'2',
lst,
1,
'ssss'
);
print('++++++++++++++++++++');
return response;
}
}