Autocomplete Text Field

import 'package:flutter/material.dart';
import 'package:autocomplete_textfield/autocomplete_textfield.dart';

import '../extensions/string_extension.dart';
import '../presentation/custom_icons.dart';

import '../model/substancia_autocomplete_option.dart';

class AutocompleteInput extends StatefulWidget {
  final List<SubstanciaAutocompleteOption> options; //int subsId, String descricao, StringprincipioAtivo, int comercialId (opitional)
  final Function submitHandler; //setState() => _mySubstancesList.add(sub)
  final int nextSub; // Integer that represents number of substances in _mySubstancesList + 1

  AutocompleteInput({
   this.options,
   this.submitHandler,
   this.nextSub,
  });

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

class _AutocompleteInputState extends State<AutocompleteInput> {
  SubstanciaAutocompleteOption _selectedOption;

  TextEditingController _controller = TextEditingController();
  bool _hasError = false;
  String errorMessage;

  GlobalKey<AutoCompleteTextFieldState<SubstanciaAutocompleteOption>> _key = new GlobalKey();

  Widget custonListTile(SubstanciaAutocompleteOption option) {
    return Card(
      elevation: 5,
      margin: EdgeInsets.only(
        top: 6,
      ),
      child: Container(
        padding: EdgeInsets.only(left: 33, top: 5, bottom: 5, right: 5),
        height: 45,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              option.descricao.capitalize(),
              style: TextStyle(
                fontSize: 16,
              ),
            ),
            if(option.descricao != option.principioAtivo)
              Text(
                option.descricao.capitalize(),
                style: TextStyle(
                  fontSize: 14,
                  color: Colors.black45
                ),
              )
          ],
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {

    print('nextSub: ${widget.nextSub}');
    return LayoutBuilder(
      builder: (ctx, constraints){
        return Row(
          mainAxisSize: MainAxisSize.max,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Expanded(
              child: AutoCompleteTextField<SubstanciaAutocompleteOption> (
                key: _key,
                controller: _controller,
                itemSubmitted: (item) {
                  setState(() {
                    _controller.text = item.descricao;
                    _selectedOption = new SubstanciaAutocompleteOption(
                      subsId: item.subsId,
                      principioAtivo: item.principioAtivo,
                      comercialId: item.comercialId,
                      descricao: item.descricao
                    );
                  });
                },
                clearOnSubmit: false,
                suggestions: widget.options,
                itemBuilder: (context, item) {
                  SubstanciaAutocompleteOption opAux = new SubstanciaAutocompleteOption(
                    subsId: item.subsId,
                    principioAtivo: item.principioAtivo,
                    descricao: item.descricao,
                    comercialId: item.comercialId
                    );
                  return custonListTile(opAux);
                },
                itemSorter: (a, b) {
                  return a.descricao.compareTo(b.descricao);
                },
                itemFilter: (item, query) {
                  return item.descricao.toLowerCase().startsWith(query.toLowerCase());
                },
                decoration: InputDecoration(
                  contentPadding: EdgeInsets.only(top: 10.0),
                  border: OutlineInputBorder(
                    borderSide: BorderSide(
                      color: Theme.of(context).primaryColor
                    )
                  ),
                  hintText: 'Informe o ${widget.nextSub}º produto',
                  labelText: 'Adicionar Produto à Mistura',
                  errorText: _hasError ? errorMessage : null,
                  prefixIcon: Icon(Custom.beaker),
                ),
                style: TextStyle(
                  fontSize: 18,
                ),
              ),
            ),
            Container(
              margin: EdgeInsets.only(left: 5),
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(6),
                boxShadow: [
                  BoxShadow(color: Colors.green, spreadRadius: 1),
                ],
              ),
              child: IconButton(
                color: Colors.white,
                icon: Icon(Icons.add),
                onPressed: () {
                  if(_selectedOption != null) {
                    _controller.clear();
                    if(!widget.submitHandler(_selectedOption)) {
                      print('entrou aqui');
                      setState(() {
                        errorMessage = "Este produto já foi selecionado!";
                        _hasError = true;
                      });
                    }
                    _selectedOption = null;
                  }
                  else {
                    // TO DO
                  }
                }
              ),
            ),
          ],
        );
      }
    );
  }
}