Flutter List.Builder fetch JSON

Question

This is my code:

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  List<User> _users = <User>[];
  List<User> _usersDisplay = <User>[];

  @override
  void initState() {
    super.initState();
    fetchUsers().then((value){
      _users.addAll(value);
      _usersDisplay = _users;
      print(_usersDisplay.length);
    });
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Users List'),
      ),
      body: SafeArea(
        child: Container(
          child: ListView.builder(
            itemBuilder: (context, index) {
              if (_usersDisplay.length > 0){
                return UserTile(user: this._usersDisplay[index]);
              }else{
                return LoadingView();
              }
            },
            itemCount: _usersDisplay.length + 1,
          ),
        ),
      ),
    );
  }
}

While executing initStae() it prints _usersDisplay.length as 100 but only return LoadingView(). It not shows UserTile().

When checking _usersDisplay.length inside of build it is always 0. Why?

Also I cannot define List as this way: List<User> _users = List<User>();

Dc7 · Accepted Answer · 2021-08-21 10:05:43Z

2

Use Future Builder for JSON & List

FutureBuilder(
  builder: (context, snapshot) {

    // WHILE THE CALL IS BEING MADE AKA LOADING
    if (ConnectionState.active != null && !snapshot.hasData) {
      return Center(child: Text('Loading'));
    }

    // WHEN THE CALL IS DONE BUT HAPPENS TO HAVE AN ERROR
    if (ConnectionState.done != null && snapshot.hasError) {
      return Center(child: Text(snapshot.error));
    }

    // IF IT WORKS IT GOES HERE!
    return ListView.builder(
      itemCount: snapshot.data.length,
      itemBuilder: (context, index) {
        return Text(snapshot.data[index].toString());
      },
    );
  },
  future: getAllTodos(),
),

answered Aug 21, 2021 at 10:05

Dc7

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2 Comments

Akila Ishan Over a year ago

How can I use Filtering or searching options when using Future Builder

Dc7 Over a year ago

Fetched data will be there in the Snapshot variable. You can access the snapshot as "snapshot.data" like list. Then, you can do whatever you want with that data.

Mathiew Abbas · Accepted Answer · 2021-08-21 10:11:17Z

1

change

fetchUsers().then((value){
      _users.addAll(value);
      _usersDisplay = _users;
      print(_usersDisplay.length);
    });

to

fetchUsers().then((value){
      _users.addAll(value);
      _usersDisplay = _users;
      print(_usersDisplay.length);
      setState(() {})
});

answered Aug 21, 2021 at 10:11

Mathiew Abbas

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1 Comment

Ravindra S. Patil Over a year ago

If you get data from API refer my answer here or here or here hope it's helpful to you in this answers I have used Futur and FutureBuilder for geting the data

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