Refresh list after deleting an item - Flutter

Question

I am trying to get the list to automatically refresh after the delete option on pop up menu is pressed. It will delete the selected item from a list of items called from an api. That item should immediately dissapear after delete is pressed on it.

API call that fills the list with api data:

  List data;

  @override
  void initState() {
    super.initState();
    this.getJsonData();
  }

  Future<String> getJsonData() async {
    var response = await http.get(
      Uri.encodeFull(url),
      headers: {"Accept": "application/json"},
    );

    var extractdata = json.decode(response.body);
    data = extractdata['levels'];
    levelsData = data;

    setState(
      () {
        var extractdata = json.decode(response.body);
        data = extractdata['levels'];
      },
    );
    return "Success";
  }

...

Api call that deletes:

  delete() async {
    String url = "http://31.183.125.253:8080/users";

    Map map = {
      'price': 1.23,
      'user_id': 'user2'
    };

    print(await apiRequest(url, map));
  }

  Future<String> apiRequest(String url, Map jsonMap) async {
    HttpClient httpClient = new HttpClient();
    HttpClientRequest request = await httpClient.deleteUrl(Uri.parse(url));
    request.headers.set('content-type', 'application/json');
    request.add(utf8.encode(json.encode(jsonMap)));
    HttpClientResponse response = await request.close();
    String statusCode = response.statusCode.toString();
    String reply = await response.transform(utf8.decoder).join();

    print(statusCode);

    httpClient.close();
    return reply;
  }

Expansion tile that stores the list from api call:

...

var levelsData = [];

  @override
  Widget build(BuildContext context) {
    List<dynamic> _getChildren() {
      List<Widget> children = [];
      levelsData.forEach(
        (element) {
            children.add(
              ListTile(
                title: Text(element['price'].toString(),
                trailing: PopUpMenu(
                  onDelete: () {
                    setState(() {
                      delete();
                    });
                  }))
            );}
      );
      return children;
    }
  }

...

Pop up menu:

class PopUpMenu extends StatelessWidget {
  VoidCallback onDelete;

  PopUpMenu({this.onDelete});

  void showMenuSelection(String value) {
    switch (value) {
      case 'Delete':
        onDelete();
        break;
      // Other cases for other menu options
    }
  }

I am able to delete the item selected to delete but the item doesnt dissapear from the list and it didnt show the changes of the list.

Answer 1

Flutter should automatically update to reflect changes to datasources. However, this is only applied after calling:

setState((){

});

So that should be run after you delete the item from the list.

Answer 2

You have to call setState and remove the item from your list.

     class _MyListViewState extends State<MyListView> {
          MyDB _myDB;
          List<MyItem> _myList;

        ...

      void getData() async {
        ...

        _myDB.getData().then((items) {
          setState(() {
            _myList = items;
          });
        });
      }

      @override
      void initState() {
        super.initState();
        getData();
      }

              @override
              Widget build(BuildContext context) {
                return (_myList== null || _myList.isEmpty)
                    ? Center(child: Text('Nothing to see...'))
                    : ListView.builder(
                        itemCount: _myList.length,
                        itemBuilder: (context, index) {
                          return

        ... onPress ...

                _myDB.deleteItem(_myList[index]).whenComplete(() {
                                                setState(() {
                                                  _myList.removeAt(index);
                                                });
                                              });