Flutter How to use DropDowns selected item on http.post-CodePudding

I have a drop down button with a list of items in it that are fetched from the api, i need to send to the server the id of the selected item. So right when the user chooses the item and presses the Start Working button i need to send the chosen items id to the server, the problem that im having is working out with sending the chosen items id.

Future<void> postLocationId(String id) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    String? authorization = prefs.getString('authorization');
    var url = 'some url';
    try {
      final response = await http.post(
        Uri.parse(url),
        headers: <String, String>{
          'authorization': authorization ?? basicAuth.toString(),
          "Content-Type": "application/json"
        },
        body: jsonEncode(id)
      );
      print(response.statusCode);
      print(id);
    } catch (er) {}
  }


  String? chooseLocation;
  late Future<Response> futureData;
  late Future<Response> futureDataForAccount;

  bool _flag = true;

  List<WorkingLocationData>? workingData;
  List<AccountData>? accountData;




 Scaffold(
            body: FutureBuilder<List<Response>>(
              future: Future.wait([futureData, futureDataForAccount]),
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  List<WorkingLocationData> data1 =
                      parsedData(snapshot.data![0].body);
                  workingData = data1;

                  AccountData data3 =
                      AccountData.fromJson(json.decode(snapshot.data![1].body));


                      child: DropdownButton<String>(

                          value: chooseLocation,
                          hint: const Text('Select a location'),
                          isExpanded: true,
                          items: workingData!.map((some) {
                            return DropdownMenuItem(
                              child: Text(some.name   ' (${some.location})'),
                              value: some.id,
                            );
                          }).toList(),
                          onChanged: (String? displayedValue) {
                            setState(
                              () {
                                chooseLocation = displayedValue!;
                              },
                            );
                          },
                        ),
                      ),
                       SizedBox(height: height * 0.150),
                      Column(
                        children: [
                          ElevatedButton(
                            onPressed: () async {
                              final WorkingLocationData locatonData = workingData!.firstWhere((some) => some.location == chooseLocation);
                              await postLocationId(locatonData.id);
                              print(locatonData.id);
                              setState(() {
                                _flag = !_flag;
                              });
                            },
                            child: Text(_flag ? 'Start Work' : 'Stop Work'),
                            style: ElevatedButton.styleFrom(
                              primary: _flag ? Colors.teal : Colors.red,
                            ),
                          ),
                        ],

CodePudding user response：

You need to add the parameter you want: postLocationId(String id).

Without changing the structure too much you can search through workingData for the item with the matching location and pass it on press like:

ElevatedButton(
  onPressed: () async {
    final WorkingLocationData locatonData = workingData!.firstWhere((some) => some.location == chooseLocation);
    postLocationId(locatonData.id);
    setState(() {
      _flag = !_flag;
    });
  },
  child: Text(_flag ? 'Start Work' : 'Stop Work'),
  style: ElevatedButton.styleFrom(
    primary: _flag ? Colors.teal : Colors.red,
  ),
),

If you're interested in a larger structural change I use https://pub.dev/packages/flutter_typeahead for this kind of thing