Flutter - ScrollController was used after being disposed - flutter

Question

class HomeScreen extends StatefulWidget {
final userName;
HomeScreen(this.userName);
#override
State<HomeScreen> createState() => _HomeScreenState();
}
Future<ClientDashboardModel?>? _meterReadingResponse;
BatchSummaryModel? _batchResponse;
AMRDashboardModel? _amrDashboardResponse;
String _userName = '';
int? qcAssignedReads = 0;
int? qcMrCompleted = 0;
int? qcCompletedReads = 0;
int? qcPendingReads = 0;
int? qcApprovedReads = 0;
int? qcRejectedReads = 0;
bool isFirstTimeCalled = false;
Timer? _timer;
int _currentIndex = 0;
final pages = [
const MDMScreen(),
const AMRDashboard(whichScreen: 0),
const AMRDashboard(whichScreen: 1),
const AMRDashboard(whichScreen: 2)
];
class _HomeScreenState extends State<HomeScreen> {
#override
void initState() {
setUpTimedFetch();
super.initState();
if (widget.userName != null) _userName = (widget.userName!);
}
#override
void dispose() {
isFirstTimeCalled = false;
_timer?.cancel();
super.dispose();
}
void setUpTimedFetch() {
if (!isFirstTimeCalled) {
_meterReadingResponse = _getDashboardData();
}
isFirstTimeCalled = true;
}
Future<ClientDashboardModel?> _getDashboardData() async {
ClientDashboardModel? meterReadingResponse;
SharedPreferences prefs = await SharedPreferences.getInstance();
String token = prefs.getString('token')!;
var responseData = await Dashboard().getClientDashboard(token);
if (responseData.statusCode == 200) {
String data = responseData.body;
var decodedData = jsonDecode(data);
meterReadingResponse = null;
meterReadingResponse = ClientDashboardModel.fromJson(decodedData);
return meterReadingResponse;
}
return null;
}
void logout() async {
SharedPreferences.getInstance().then((value) {
value.remove('token');
value.remove('userName');
});
Navigator.pushReplacement(context, MaterialPageRoute(builder: (context) {
return const LoginScreen();
}));
}
Future<void> _showMyDialog() async {
return showDialog<void>(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return AlertDialog(
title: const Text(Strings.kLogoutLabel),
content: const Text(Strings.kConfirmLogout),
actions: <Widget>[
TextButton(
child: const Text(Strings.kCancelLabel),
onPressed: () {
Navigator.of(context).pop();
},
),
TextButton(
child: const Text(Strings.kOKLabel),
onPressed: () {
Navigator.of(context).pop();
logout();
},
)
],
);
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
bottomNavigationBar: BottomNavigationBar(
type: BottomNavigationBarType.fixed,
currentIndex: _currentIndex,
backgroundColor: const Color(0XFF116AFF),
unselectedItemColor: Colors.white,
selectedLabelStyle: const TextStyle(color: Colors.white),
showUnselectedLabels: false,
onTap: (value) {
setState(() => _currentIndex = value);
},
items: [
BottomNavigationBarItem(
label: 'MDM',
icon: Container(
decoration: BoxDecoration(
color:
_currentIndex == 0 ? Colors.white : Colors.transparent,
shape: BoxShape.circle),
child: const Padding(
padding: EdgeInsets.all(10.0),
child: Icon(Icons.electric_meter_outlined),
),
),
),
BottomNavigationBarItem(
label: 'Site Survey',
icon: Container(
decoration: BoxDecoration(
color:
_currentIndex == 1 ? Colors.white : Colors.transparent,
shape: BoxShape.circle),
child: const Padding(
padding: EdgeInsets.all(10.0),
child: Icon(Icons.location_city_outlined),
),
),
),
BottomNavigationBarItem(
label: 'Meter Replace',
icon: Container(
decoration: BoxDecoration(
color:
_currentIndex == 2 ? Colors.white : Colors.transparent,
shape: BoxShape.circle),
child: const Padding(
padding: EdgeInsets.all(10.0),
child: Icon(Icons.library_books_outlined),
),
),
),
BottomNavigationBarItem(
label: 'TroubleShoot',
icon: Container(
decoration: BoxDecoration(
color:
_currentIndex == 3 ? Colors.white : Colors.transparent,
shape: BoxShape.circle),
child: const Padding(
padding: EdgeInsets.all(10.0),
child: Icon(Icons.info_outline),
),
),
),
],
),
appBar: AppBar(
automaticallyImplyLeading: false,
title: const Text(Strings.kMRDLabel),
actions: [
IconButton(
onPressed: () {
_showMyDialog();
},
icon: const Icon(Icons.power_settings_new))
],
),
body: childView());
}
Widget childView() {
return SingleChildScrollView(
scrollDirection: Axis.vertical,
child: Padding(
padding: const EdgeInsets.all(20.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
Strings.kWelcome2Label,
style: TextStyle(
color: Colors.amber.shade700,
fontSize: 16.0,
fontWeight: FontWeight.w600),
),
Text(
_userName.toTitleCase(),
style: const TextStyle(
color: Colors.black,
fontSize: 16.0,
fontWeight: FontWeight.w400),
)
],
),
const Spacer(),
ClipRRect(
borderRadius: BorderRadius.circular(10),
child: Container(
padding: const EdgeInsets.all(10),
decoration: BoxDecoration(color: Colors.grey.shade200),
child: SvgPicture.asset(
'images/profile.svg',
height: 54.0,
width: 54.0,
),
),
),
],
),
const SizedBox(
height: 30,
),
Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: [pages[_currentIndex]],
),
],
),
));
}
}
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:manager/components/dotted_line.dart';
import 'package:manager/model/lookup_cycle.dart';
import 'package:manager/model/mr_report_model.dart';
import 'package:manager/services/dashboard_service.dart';
import 'package:manager/utils/debouncer.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:manager/utils/string_captialize.dart';
class MRPerformance extends StatefulWidget {
const MRPerformance({super.key});
#override
State<MRPerformance> createState() => _MRPerformanceState();
}
bool isFilter = false;
bool isPerformingRequest = false;
int pageNumber = 0;
String _chosenValue = '';
List<MRReportResult> users = [];
Future<List<String>?>? dropDownValue;
ScrollController _scrollController = ScrollController();
final _debouncer = Debouncer(milliseconds: 500);
class _MRPerformanceState extends State<MRPerformance> {
#override
void initState() {
super.initState();
_getMoreData(_chosenValue);
dropDownValue = getAllCategory();
_scrollController.addListener(() {
if (_scrollController.position.pixels ==
_scrollController.position.maxScrollExtent) {
pageNumber++;
_getMoreData(_chosenValue);
}
});
}
Future<List<String>?>? getAllCategory() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String token = prefs.getString('token')!;
var cycleResponse = await Dashboard().getAllCycle(token);
try {
if (cycleResponse.statusCode == 200) {
List<String> items = [];
var jsonData = json.decode(cycleResponse.body) as List;
List<LookUpCycle> lookupCycle = jsonData
.map<LookUpCycle>((json) => LookUpCycle.fromJson(json))
.toList();
items.add('Select');
for (var element in lookupCycle) {
if (element.name != null) {
items.add(element.name!);
}
}
return items;
}
} catch (ex) {
throw (ex.toString());
}
return null;
}
#override
void dispose() {
super.dispose();
_scrollController.dispose();
}
void _getMoreData(String searchCycle) async {
List<MRReportResult>? resultResponse = [];
if (!isPerformingRequest) {
setState(() {
isPerformingRequest = true;
});
SharedPreferences prefs = await SharedPreferences.getInstance();
String token = prefs.getString('token')!;
debugPrint(token);
var responseData =
await Dashboard().getMRReport(token, pageNumber, 10, searchCycle);
if (responseData.statusCode == 200) {
String data = responseData.body;
var decodedData = jsonDecode(data);
MRReportModel newEntries = MRReportModel.fromJson(decodedData);
if (newEntries.result == null) {
if (newEntries.result!.isEmpty) {
double edge = 50.0;
double offsetFromBottom =
_scrollController.position.maxScrollExtent -
_scrollController.position.pixels;
if (offsetFromBottom < edge) {
_scrollController.animateTo(
_scrollController.offset - (edge - offsetFromBottom),
duration: const Duration(milliseconds: 500),
curve: Curves.easeOut);
}
}
}
setState(() {
users.addAll(newEntries.result!);
isPerformingRequest = false;
});
}
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
resizeToAvoidBottomInset: false,
appBar: AppBar(title: const Text('MR Performance')),
body: filterView());
}
void setFilterState() {
setState(() {
if (isFilter == true) {
isFilter = false;
} else {
isFilter = true;
}
});
}
Widget _buildProgressIndicator() {
return Padding(
padding: const EdgeInsets.all(8.0),
child: Center(
child: Opacity(
opacity: isPerformingRequest ? 1.0 : 0.0,
child: const CircularProgressIndicator(),
),
),
);
}
Widget filterView() {
return Column(
children: [
Row(
children: [
Visibility(
visible: isFilter ? true : false,
child: Flexible(
child: Card(
shape: RoundedRectangleBorder(
side: const BorderSide(color: Color(0XFFDCDCDC)),
borderRadius: BorderRadius.circular(10)),
elevation: 2,
child: Column(
children: [
Row(
children: [
Expanded(
child: TextField(
textInputAction: TextInputAction.search,
decoration: const InputDecoration(
border: InputBorder.none,
prefixIcon: InkWell(
child: Icon(Icons.search),
),
contentPadding: EdgeInsets.all(8.0),
hintText: 'Search ',
),
onChanged: (string) {
_debouncer.run(() {});
},
),
),
],
),
],
),
),
),
),
Visibility(
visible: isFilter ? false : true,
child: Flexible(
child: Card(
elevation: 4,
shape: RoundedRectangleBorder(
side: const BorderSide(color: Color(0XFFDCDCDC)),
borderRadius: BorderRadius.circular(10)),
child: Padding(
padding: const EdgeInsets.only(
left: 10,
),
child: FutureBuilder<List<String>?>(
future: dropDownValue,
builder: (context, snapshot) {
if (snapshot.connectionState ==
ConnectionState.done) {
if (snapshot.hasError) {
return const Text('Something wrong');
} else if (snapshot.hasData) {
var data = snapshot.data!;
return DropdownButtonHideUnderline(
child: DropdownButton<String>(
icon: const Icon(
Icons.expand_more_outlined,
size: 35,
color: Color(0XFF116AFF),
),
borderRadius: BorderRadius.circular(10),
isExpanded: true,
// value: _chosenValue.isNotEmpty ? _chosenValue : null,
elevation: 16,
style: const TextStyle(
color: Colors.black,
fontSize: 14,
fontWeight: FontWeight.w400),
items: data.map((String value) {
return DropdownMenuItem(
value: value, child: Text(value));
}).toList(),
hint: Padding(
padding: const EdgeInsets.all(15),
child: Text(
_chosenValue.isEmpty
? 'Cycle'
: _chosenValue,
style: const TextStyle(
color: Colors.black,
fontSize: 16,
fontWeight: FontWeight.w400),
),
),
onChanged: (String? value) {
setState(() {
if (value != null) {
pageNumber = 0;
users.clear();
if (value == 'Select') {
_chosenValue = '';
} else {
_chosenValue = value;
}
_getMoreData(_chosenValue);
}
});
},
),
);
}
}
return const CircularProgressIndicator();
},
)),
),
),
),
InkWell(
onTap: () => {setFilterState()},
child: Card(
elevation: 4,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10)),
child: Padding(
padding: const EdgeInsets.all(10.0),
child: isFilter
? const Icon(Icons.filter_alt, color: Color(0XFF116AFF))
: const Icon(
Icons.search,
color: Color(0XFF116AFF),
),
),
),
),
],
),
Expanded(
child: ListView.builder(
shrinkWrap: true,
scrollDirection: Axis.vertical,
itemCount: users.length + 1,
controller: _scrollController,
itemBuilder: (BuildContext context, int index) {
if (index == users.length) {
return _buildProgressIndicator();
} else {
return cardView(users, index);
}
}),
),
],
);
}
Widget cardView(List<MRReportResult>? users, int index) {
return Card(
shape: RoundedRectangleBorder(
side: const BorderSide(color: Color(0XFFDCDCDC)),
borderRadius: BorderRadius.circular(10)),
margin: const EdgeInsets.all(8),
child: Padding(
padding: const EdgeInsets.all(10.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
children: [
Container(
decoration: BoxDecoration(
border: Border.all(
color: Colors.orange,
),
borderRadius: const BorderRadius.all(Radius.circular(20))),
margin: const EdgeInsets.all(10),
padding: const EdgeInsets.all(10),
child: Row(
children: [
Text(
'${users?[index].mRNumber}: ',
style: const TextStyle(
color: Colors.orange,
fontSize: 10,
fontWeight: FontWeight.w600),
),
Text(
'${users?[index].meterReaderName}'.toTitleCase(),
style: const TextStyle(
color: Colors.black,
fontSize: 10,
fontWeight: FontWeight.w400),
),
],
),
),
Padding(
padding: const EdgeInsets.only(left: 20),
child: Row(
children: [
const Text(
'Supervisor: ',
style: TextStyle(
color: Color(0XFF004AC6),
fontSize: 10,
fontWeight: FontWeight.w600),
),
Expanded(
child: Text(
'${users?[index].supervisor}'.toTitleCase(),
overflow: TextOverflow.fade,
style: const TextStyle(
color: Colors.black,
fontSize: 10,
fontWeight: FontWeight.w400),
),
),
],
),
),
const SizedBox(height: 10),
const MySeparator(),
const SizedBox(height: 10),
Padding(
padding: const EdgeInsets.only(left: 30, right: 30),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Row(
children: [
Column(
children: [
Text(
'${users?[index].unreadPercenatge}%',
style: const TextStyle(
color: Colors.orange,
fontSize: 10,
fontWeight: FontWeight.w600),
),
const Text(
'Unread',
style: TextStyle(
color: Color(0XFF004AC6),
fontSize: 12,
fontWeight: FontWeight.w400),
)
],
)
],
),
Row(
children: [
Column(
children: [
Text(
'${users?[index].readPercenatge}%',
style: const TextStyle(
color: Colors.green,
fontSize: 10,
fontWeight: FontWeight.w600),
),
const Text(
'Read',
style: TextStyle(
color: Color(0XFF004AC6),
fontSize: 12,
fontWeight: FontWeight.w400),
)
],
)
],
),
Row(
children: [
Column(
children: [
Text(
'${users?[index].plusorMinusTwoReadPercentage}%',
style: const TextStyle(
color: Colors.green,
fontSize: 10,
fontWeight: FontWeight.w600),
),
const Text(
'+/- 2',
style: TextStyle(
color: Color(0XFF004AC6),
fontSize: 12,
fontWeight: FontWeight.w400),
)
],
)
],
),
Row(
children: [
Column(
children: [
Text(
'${users?[index].above32ReadPercentage}%',
style: const TextStyle(
color: Colors.orange,
fontSize: 10,
fontWeight: FontWeight.w600),
),
const Text(
'>32',
style: TextStyle(
color: Color(0XFF004AC6),
fontSize: 12,
fontWeight: FontWeight.w400),
)
],
)
],
),
],
),
),
],
),
),
);
}
}
════════ Exception caught by widgets library ═══════════════════════════════════
The following assertion was thrown building Builder:
A ScrollController was used after being disposed.
Once you have called dispose() on a ScrollController, it can no longer be used.
The relevant error-causing widget was
MaterialApp
lib/main.dart:13
When the exception was thrown, this was the stack

Answer 1

You have declared _getMoreData two times in init(), so remove it before _scrollController as shown below
void initState() {
super.initState();
_getMoreData(_chosenValue);-------------> remove this from here
dropDownValue = getAllCategory();
_scrollController.addListener(() {
if (_scrollController.position.pixels ==
_scrollController.position.maxScrollExtent) {
pageNumber++;
_getMoreData(_chosenValue);
}
});
}
OR
Declare ScrollController _scrollController = ScrollController(); in state class _MRPerformanceState as below code:
class _MRPerformanceState extends State<MRPerformance> {
ScrollController _scrollController = ScrollController();