is there a way to upload data from a FormField with a dropdown list to firebase...im get null value after uploading to firebase

Question

this is the formField that is uploading no value i tried using a controller but seems now event compatible.the rest of the textformfields are working but i dont know why the formField is uploading a empty value to the firebase

 Container(
            margin: const EdgeInsets.only(left: 15, top: 10, right: 15),
            child: FormField<String>(
              builder: (FormFieldState<String> state) {
                return InputDecorator(
                  decoration: InputDecoration(
                    contentPadding:
                        const EdgeInsets.fromLTRB(12, 10, 20, 20),
                    labelText: "EVENT TYPE/CATEGORY",
                    border: OutlineInputBorder(
                      borderRadius: BorderRadius.circular(10.0),
                    ),
                  ),
                  isEmpty: eventcategoryChoosen == null ||
                      eventcategoryChoosen == '',
                  child: DropdownButtonHideUnderline(
                    child: DropdownButtonFormField<EventCatListDataModel>(
                      validator: (_eventcategoryChoosen) {
                        if (_eventcategoryChoosen == null) {
                          return ("section cannot be Empty");
                        }
                        print(_eventcategoryChoosen);
                        return null;
                      },
                      onSaved: (_eventcategoryChoosen) {
                        setState(() {
                          eventcategoryEditingController.text =
                              _eventcategoryChoosen! as String;
                        });
                        print(_eventcategoryChoosen);
                      },
                      style: const TextStyle(
                        fontSize: 16,
                        color: blue,
                      ),
                      hint: const Text(
                        "Select Event",
                        style: TextStyle(
                          color: green,
                          fontSize: 16,
                        ),
                      ),
                      isExpanded: true,
                      value: eventcategoryChoosen,
                      isDense: true,
                      onChanged: (newSelectedBank) async {
                        _onDropDownItemSelected(newSelectedBank!);
                        setState(() {
                          eventcategoryChoosen = newSelectedBank;
                          state.didChange(newSelectedBank.toString());
                        });

                        print(eventcategoryChoosen.toString());
                      },
                      items: eventcategoryList
                          .map<DropdownMenuItem<EventCatListDataModel>>(
                              (EventCatListDataModel category) {
                        return DropdownMenuItem(
                          value: category,
                          child: Row(
                            // mainAxisAlignment: MainAxisAlignment.spaceBetween,
                            children: [
                              CircleAvatar(
                                child: Image.asset(category.eventlogo),
                              ),
                              // Icon(valueItem.eventlogo),
                              const SizedBox(
                                width: 15,
                              ),

                              Text(
                                category.eventname,
                                style: const TextStyle(color: cyanwe),
                              ),
                            ],
                          ),
                        );
                      }).toList(),
                    ),
                  ),
                );
              },
            ),
          ),

this is the how the events model ,how we upload to firebase.but after each upload the 'eventcatecogty' field is empty.

import 'package:cloud_firestore/cloud_firestore.dart';

class EventsModel {
  late String eventName;
  late String date;
  late String gateopens;
  late int ticketPrice;
  late String quantityofticket;
  late String descriptionevent;
  late String locationevent;
  late String eventcategoryChoosen;
  late List<String> imagesUrl;
  EventsModel(
      {required this.eventName,
      required this.date,
      required this.gateopens,
      required this.ticketPrice,
      required this.quantityofticket,
      required this.descriptionevent,
      required this.locationevent,
      required this.imagesUrl,
      required this.eventcategoryChoosen});
  CollectionReference db = FirebaseFirestore.instance.collection('events');
   Future<void> addEvent(EventsModel eventModel) async {
    Map<String, dynamic> data = {
     "eventName": eventModel.eventName,
  "date": eventModel.date,
  "gateopens": eventModel.gateopens,
  "ticketPrice": eventModel.ticketPrice,
  "quantityofticket": eventModel.quantityofticket,
  "descriptionevent": eventModel.descriptionevent,
  "locationevent": eventModel.locationevent,
  "imagesUrl": eventModel.imagesUrl,
  "eventcategory": eventModel.eventcategoryChoosen,
    };
await db.add(data);
  }

}

this is the class model feeding the dropdown. im trying to figure out why my code is not uploading event caterory.help!!

    class EventCatListDataModel {
  String eventname;

  String eventlogo;

  EventCatListDataModel({required this.eventname, required        this.eventlogo});
}

List<EventCatListDataModel> eventcategoryList = [
  EventCatListDataModel(eventlogo: "assets/icons/club.png",     eventname: 'Club'),
  EventCatListDataModel(
  eventlogo: "assets/icons/concert.png", eventname: "Concerts"),
  EventCatListDataModel(
  eventlogo: "assets/icons/road-trip.png", eventname: "road-trip"),
  EventCatListDataModel(
  eventlogo: "assets/icons/camping.png", eventname: 'camping'),

  EventCatListDataModel(
  eventlogo: "assets/images/category/salad.png",
  eventname: "sunday branch"),
  EventCatListDataModel(
  eventlogo: "assets/icons/motorbike.png", eventname: "Motobike meet"),
  EventCatListDataModel(
  eventlogo: "assets/icons/car.png", eventname: "Car meet"),
  
];