Class 'Future<dynamic>' has no instance getter 'length' - dart

Question

Im trying to get LayoutBuilder working with some items from my API.
with this code :
class _ContactsScreenState extends State<ContactsScreen> {
final _contacts = _dummyData();
final _selection = ValueNotifier<ResumenPublicaciones>(null);
#override
void initState() {
super.initState();
}
#override
Widget build(BuildContext context) {
var futureBuilder = new FutureBuilder(
future: _dummyData(),
builder: (BuildContext context, AsyncSnapshot snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
case ConnectionState.waiting:
return new Text('loading...');
default:
if (snapshot.hasError)
return new Text('Error: ${snapshot.error}');
else
return buildLayoutBuilder();
}
},
);
return new Scaffold(
body: futureBuilder,
);
}
LayoutBuilder buildLayoutBuilder() {
return LayoutBuilder(builder: (context, dimens) {
if (dimens.maxWidth >= kTabletBreakpoint) {
const kListViewWidth = 300.0;
return Row(
children: <Widget>[
Container(
width: kListViewWidth,
child: buildListView((val) {
_selection.value = val;
}),
),
VerticalDivider(width: 0),
Expanded(
child: ValueListenableBuilder<ResumenPublicaciones>(
valueListenable: _selection,
builder: (context, contact, child) {
if (contact == null) {
return Scaffold(
appBar: AppBar(),
body: Center(child: Text('No Contact Selected')),
);
}
return ContactDetails(contact: contact);
},
))
],
);
}
return buildListView((val) {
Navigator.of(context).push(
MaterialPageRoute(
builder: (_) => ContactDetails(contact: val),
),
);
});
});
}
Widget buildListView(ValueChanged<ResumenPublicaciones> onSelect) {
return Scaffold(
appBar: AppBar(
centerTitle: false,
title: Text('Contacts'),
),
body: ListView.separated(
separatorBuilder: (context, index) => Divider(height: 0),
itemCount: _contacts.length,
itemBuilder: (context, index) {
final _contact = _contacts[index];
return ListTile(
leading: Icon(Icons.person),
title: Text(_contact.name),
subtitle: Text(_contact.count),
onTap: () => onSelect(_contact),
);
},
),
);
}
}
_dummyData() async {
var res = await fetchJobs(http.Client());
return res;
}
Im receiving this error : Class 'Future' has no instance getter 'length'.
Any Idea on how could I do this? Ias per what I read, I would need to do somethin like var _contact = Await dummyData(). But im not sure where should where.

Answer 1

You can't await in field initializers or in constructors. Your best choice is to keep the type of _contacts as Future<Object>, and then await it where you use the value:
itemCount: (await _contacts).length
That makes your build method asynchronous, which I believe is an issue for Flutter. You may need to use a FutureBuilder.