Invalid value: Only valid value is 0: 1 in Flutter - rest

Question

I create an UI with FutureBuilder to show an nested object from my rest api, but i don't know why, but after run my function(in my UI) my console throw me this type of error:
RangeError (index): Invalid value: Only valid value is 0: 1
I try flutter doctor but it not help me,
ps. I can't use itemCount: snapshot.data.length because
Class 'User' has no instance getter 'length'
my code:
#override
void initState(){
super.initState();
userApiService = UserApiService();
_future = getUserData();
}
getUserData() async{
sharedPreferences = await SharedPreferences.getInstance();
int id = sharedPreferences.getInt('id');
return userApiService.getUser(id);
}
#override
Widget build(BuildContext context){
return FutureBuilder(
future: _future,
builder: (context, snapshot){
if(!snapshot.hasData){
return Scaffold(
body: Center(
child: CircularProgressIndicator(),
),
);
}
// User user = snapshot.data;
return Scaffold(
backgroundColor: Colors.white,
body: Container(
child: ListView.builder(
itemBuilder: (context, i){
User user = snapshot.data;
return GestureDetector(
onTap: () {
//
},
child: Container(
width: 300,
height: 80,
color: Colors.blue,
child: Text(user.myFollows[i].firstName + ' ' + user.myFollows[i].lastName),
),
);
}
)
),
);
},
);
}
model User:
class User {
List<Observations> followedBy;
List<Observations> myFollows;
int id;
String firstName;
String lastName;
User(
{
this.followedBy,
this.myFollows,
this.id,
this.firstName,
this.lastName,
});
factory User.fromJson(Map<String, dynamic> json){
return User(
id: json['id'],
firstName: json['firstName'],
lastName: json['lastName'],
followedBy: parseFollowedBy(json),
myFollows: parseMyFollows(json),
);
}
static List<Observations> parseFollowedBy(json){
var lista = json['followedBy'] as List;
List<Observations> followedByList = lista.map((data) => Observations.fromJson(data)).toList();
return followedByList;
}
static List<Observations> parseMyFollows(myFollowsJson){
var list = myFollowsJson['myFollows'] as List;
List<Observations> myFollowsList = list.map((data) => Observations.fromJson(data)).toList();
return myFollowsList;
}
}
List<User> usersFromJson(String jsonData){
final data = json.decode(jsonData);
return List<User>.from(data.map((item) => User.fromJson(item)));
}
User userFromJson(String jsonData){
final data = json.decode(jsonData);
return User.fromJson(data);
}
String userToJson(User data){
final jsonData = data.toJson();
return json.encode(jsonData);
}
model observations.dart:
class Observations {
final int id;
final String firstName;
final String lastName;
Observations({this.id, this.firstName, this.lastName});
factory Observations.fromJson(Map<String, dynamic> parsedJson) {
return Observations(
id: parsedJson['id'],
firstName: parsedJson['firstName'],
lastName: parsedJson['lastName'],
);
}
}
thanks for any help :)

Answer 1

In this case you have to set itemCount to the lenght of the list you are traversing in the ListView.
I see you are using user.myFollows[i]
So maybe you should use:
itemCount: user.myFollows.length,