Custom dropdown to return document so that i can add document values to multiple columns in collection

Help

I need custom dropdown who will get collection from database then he will show document.name as label and on selection will return selected item/document so that i can save country/state/city in user.country user.state user.city.

I have collection of city names with country, state, city columns and i wish to store all those data in the user. How can i get returned record and use in the string value, i assume i can do something returned object.mesto (city) on Serbian.

// Automatic FlutterFlow imports
import '/backend/backend.dart';
import '/backend/schema/structs/index.dart';
import '/flutter_flow/flutter_flow_theme.dart';
import '/flutter_flow/flutter_flow_util.dart';
import '/custom_code/widgets/index.dart'; // Imports other custom widgets
import '/custom_code/actions/index.dart'; // Imports custom actions
import '/flutter_flow/custom_functions.dart'; // Imports custom functions
import 'package:flutter/material.dart';
// Begin custom widget code
// DO NOT REMOVE OR MODIFY THE CODE ABOVE!

class DdFiUlaz extends StatefulWidget {
  const DdFiUlaz({
    Key? key,
    required this.width,
    required this.height,
    required this.fiUlaz,
    this.odabranoMestoId,
    required this.onChangeCustom,
  }) : super(key: key);

  final double? width;
  final double? height;
  final List<FiUlazRecord> fiUlaz;
  final String? odabranoMestoId;
  final Future<dynamic> Function() onChangeCustom;

  @override
  _DdFiUlazState createState() => _DdFiUlazState();
}

class _DdFiUlazState extends State<DdFiUlaz> {
  FiUlazRecord? selectedValue;

  @override
  void initState() {
    super.initState();
    if (widget.odabranoMestoId != null) {
      selectedValue = widget.fiUlaz.firstWhere(
        (item) => item.mesto == widget.odabranoMestoId,
        orElse: () => widget.fiUlaz.first,
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      width: widget.width,
      height: widget.height,
      child: DropdownButton<FiUlazRecord>(
        hint: Text('Odaberi Mesto'),
        value: selectedValue,
        onChanged: (FiUlazRecord? newValue) {
          setState(() {
            selectedValue = newValue;
          });
          if (widget.onChangeCustom != null) {
            widget.onChangeCustom();
          }
        },
        items: widget.fiUlaz.map((FiUlazRecord fiUlaz) {
          return new DropdownMenuItem<FiUlazRecord>(
            value: fiUlaz,
            child: new Text(fiUlaz.naziv),
          );
        }).toList(),
      ),
    );
  }
}