flutter TabBarView sometimes not triggering on gesture swipe - flutter

Question

I am using Flutter -Android studio. I have main screen with TabBarView control (2 pages). each page get data from sqfite database. both have same statefull widget class, but I pass parameter to look into database and display.
Issue : when I click tabbar header , data displayed is Ok. But when I swipe tabs, it sometimes work and sometimes does not work. as per below video. I have check and seems that Build event is not trigger every if Swipe was done.
Main widget with tabbarview
screen record
Note that 1st tab has only 1 record, while second has 6 records. tabClick works fine, but swipe sometime not work properly.
body: TabBarView(
controller: _tabController,
children: [
DisplayTransactions(
tmptransType: TransactionType.enIncome,
transacBloc: _transacBloc,
SelectedItemsCount: bRowSelectionCount,
onSelectionChanged: (count) {
setState(() {
bRowSelectionCount = count;
});
},
),
// Center(child: Text("Page 1")),
DisplayTransactions(
tmptransType: TransactionType.enExpense,
transacBloc: _transacBloc,
SelectedItemsCount: bRowSelectionCount,
onSelectionChanged: (count) {
setState(() {
bRowSelectionCount = count;
});
},
//Center(child: Text("Page 2")),
)
],
),
------ > Widget to display data into listview for each tabbar page
class DisplayTransactions extends StatefulWidget {
final TransactionType tmptransType;
final FinanceTransBlock transacBloc;
final Function onSelectionChanged;
int SelectedItemsCount;
/// -1 expense 1 income
DisplayTransactions(
{Key key,
#required this.tmptransType,
#required this.transacBloc,
this.SelectedItemsCount,
this.onSelectionChanged})
: super(key: key);
#override
_DisplayTransactionsState createState() => _DisplayTransactionsState();
}
class _DisplayTransactionsState extends State<DisplayTransactions> {
var isSelected = false;
var mycolor = Colors.white;
// int iselectionCount = 0;
#override
Widget build(BuildContext context) {
widget.transacBloc.transacType = widget.tmptransType;
debugPrint("----------------------------- ${widget.tmptransType}");
if (widget.SelectedItemsCount == 0) {// if no rows selected, then reload database based on trans type, eg expense, or income.. etc
widget.transacBloc.refresh();
}
return StreamBuilder<List<FinanceTransaction>>(
stream: widget.transacBloc.transacations,
builder: (context, snapshot) {
if (snapshot.hasData) {
List<FinanceTransaction> list = snapshot.data;
// return buildTaskListWal(snapshot.data);
return Padding(

Answer 1

It looks like the app is taking some time to retrieve the new data. Try checking for null on the snapshot.data and display a circularProgressIndicator.
if (snapshot.data == null) {
return CirgularProgressIndicator();
} else {
//display data
}