Listview show nothing with asynchronous method - flutter

Question

I don't know why when I build my project, no error are return but my listview is empty..
The class :
final LocationService service = LocationService();
late Future<List<Location>> _locations;
#override
void initState() {
super.initState();
_locations = service.getLocations();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Mes locations'),
),
bottomNavigationBar: const BottomNavBar(2),
body: Center(
child: FutureBuilder<List<Location>>(
future: _locations,
builder:
(BuildContext context, AsyncSnapshot<List<Location>> response) {
List<Widget> children;
if (response.hasData) {
children = <Widget>[
ListView.builder(
itemCount: response.data?.length,
itemBuilder: (context, index) =>
_BuildRow(response.data?[index]),
itemExtent: 285,
),
];
} else if (response.hasError) {
children = <Widget>[
const Icon(
Icons.error_outline,
color: Colors.red,
size: 40,
),
const Padding(
padding: EdgeInsets.only(top: 16),
child: Text('Un problème est survenu'),
),
];
} else {
children = const <Widget>[
SizedBox(
width: 50,
height: 50,
child: CircularProgressIndicator(
strokeWidth: 6,
),
),
];
}
return Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: children,
),
);
}),
),
);
}
// ignore: non_constant_identifier_names
_BuildRow(Location? location) {
return Column(
children: [
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Column(
children: [
Text(
"OKOK",
style: LocationTextStyle.priceBoldGreyStyle,
),
Text("${location?.dateFin}")
],
),
Text("${location?.montanttotal}€")
],
)
],
);
}
I have print my response.data?.length and it not empty.
At first it gave me the error "has size" but now the debug console is empty too...
You can find my project on GitLab : https://gitlab.com/victor.nardel/trash-project-flutter
Thank you in advance for your help

Answer 1

the error is caused by ListView.builder
simple solution:
wrap your ListView with Expanded
if (response.hasData) {
children = <Widget>[
Expanded(
child:ListView.builder(
....
for better code: just return the Widget, not List of widget.
something like below:
if(hasdata) return Listview();
else if(has error) return Column();
else return CircularIndicator();
so you can avoid redundant Widget.