LateInitializationError: Field 'userModels' has not been initialized - flutter

Question

So I am trying to get list of data that is provided by user as an input and display them by creating list of card but when I run the project I come up with an error LateInitializationError: Field 'userModels' has not been initialized. Not sure what is wrong with the code or I missed anything on the code.
class UserPage extends StatefulWidget {
#override
_UserPageState createState() => _UserPageState();
}
class _UserPageState extends State<UserPage> {
late List<UserModels>? userModels;
bool isLoading = false;
#override
void initState() {
super.initState();
refreshUserPage();
}
#override
void dispose() {
RegDatabase.instance.close();
super.dispose();
}
Future refreshUserPage() async {
setState(() => isLoading = true);
**//this.userModels = await RegDatabase.instance.readAllNotes();**
setState(() => isLoading = false);
}
#override
Widget build(BuildContext context) => Scaffold(
appBar: AppBar(
title: Text(
'Notes',
style: TextStyle(fontSize: 24),
),
actions: [Icon(Icons.search), SizedBox(width: 12)],
),
body: Center(
child: isLoading
? CircularProgressIndicator()
: userModels!.isEmpty
? Text(
'No Notes',
style: TextStyle(color: Colors.white, fontSize: 24),
)
: buildNotes(userModels),
),
floatingActionButton: FloatingActionButton(
backgroundColor: Colors.black,
child: Icon(Icons.add),
onPressed: () async {
await Navigator.of(context).push(
MaterialPageRoute(builder: (context) => AddEditUserPage()),
);
refreshUserPage();
},
),
);
Widget buildNotes(userModels) => Container(
child: ListView.builder(
itemCount: userModels.length,
padding: const EdgeInsets.only(top: 10.0),
itemBuilder: (context, index) {
return BabyCard(userModels[index]);
})
);
}

Answer 1

From your codes I understand that userModel can also be null but you are checking if its empty. you can also add if its null
body: Center(
child: isLoading
? CircularProgressIndicator()
: userModels == null || userModels!.isEmpty
? Text(
'No Notes',
style: TextStyle(color: Colors.white, fontSize: 24),
)
: buildNotes(userModels),
),
And don't mark userModels as late since you are adding ? it means it can be null too.
List<UserModels>? userModels;

Answer 2

You're making initState forced to be executed to completion with Futures left uncompleted. initState must be synchronous (cannot be async) and should not call any Future-producing routine (directly or indirectly) except to store that Future into a variable for later review.

Answer 3

Just change this line :
late List<UserModels>? userModels;
To this one :
List<UserModels> userModels = [];