Cant get length in listview.builder in Flutter - flutter

Question

I'm learning flutter and dart language and trying to apply bloc pattern by rxdart and show data in the page.
Can't get length or display a data in page stream builder and listview.builder because I receive error:
class 'Future<List<User>>' has no instance getter 'length'.
Receiver: Instance of 'Future<List<User>>'
Tried calling: length
My class user.dart
class User {
int id;
String name;
String username;
String email;
User({this.id, this.name, this.username, this.email});
User.fromJson(Map<String, dynamic> parsedJson) {
User(
id: parsedJson['id'],
name: parsedJson['name'],
username: parsedJson['username'],
email: parsedJson['email'],
);
}
}
// user_repo.dart
import 'package:learn_flutter_bloc/bloc_rx_example/User.dart';
import 'package:http/http.dart' as http;
import 'dart:async';
import 'dart:convert';
import 'package:learn_flutter_bloc/url.dart';
class UserRepo {
static Future<List<User>> getUsers() async {
final res = await http.get("https://jsonplaceholder.typicode.com/users");
List<User> users = [];
if (res.statusCode == 200) {
var data = jsonDecode(res.body);
for (var user in data) {
users.add(User.fromJson(user));
}
return users;
} else {
throw Exception("Error In Calling APi");
}
}
}
// user_bloc
import 'package:learn_flutter_bloc/bloc_base.dart';
import 'package:learn_flutter_bloc/bloc_rx_example/user_repo.dart';
import 'package:rxdart/subjects.dart';
class UserBloc extends BlocBase {
Subject _usersSubject = BehaviorSubject();
Stream get users => _usersSubject.stream;
getUsers() async {
var usersData = UserRepo.getUsers();
_usersSubject.add(usersData);
}
#override
dispose() {
_usersSubject.close();
}
}
final bloc = UserBloc();
// user_list_app.dart
import 'package:flutter/material.dart';
import 'package:learn_flutter_bloc/bloc_rx_example/user_bloc.dart';
class UserListApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Bloc Rx Example',
theme: ThemeData(
primaryColor: Colors.teal,
),
home: Scaffold(
appBar: AppBar(
title: Text('Bloc Rx Example'),
leading: IconButton(
icon: Icon(Icons.arrow_back),
onPressed: () {
Navigator.of(context).pop();
}),
),
body: UserList(),
),
);
}
}
class UserList extends StatefulWidget {
#override
_UserListState createState() => _UserListState();
}
class _UserListState extends State<UserList> {
#override
void dispose() {
bloc.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
bloc.getUsers();
return Padding(
padding: EdgeInsets.all(10.0),
child: StreamBuilder(
stream: bloc.users,
builder: (context, snapshot) {
if (snapshot.hasData) {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (context, index) {
return ListTile(
leading: Icon(Icons.weekend),
title: Text('${snapshot.data[index].name}'),
);
});
} else if (!snapshot.hasError) {
return Text(snapshot.error.toString());
} else {
return Center(
child: CircularProgressIndicator(),
);
}
},
),
);
}
}

Answer 1

While you are using StreamBuilder in the UI, Your getUsers() is returning Future<List<User>> . Return Stream<<List<User>> from getUsers() .

Answer 2

Fixed I problem was in bloc_user.dart misssing await
Future<List<User>> getUsers() async {
var usersData = UserRepo.getUsers();
print(usersData);
_usersSubject.sink.add(usersData);
}
to
Future<List<User>> getUsers() async {
var usersData = await UserRepo.getUsers();
print(usersData);
_usersSubject.sink.add(usersData);
}