Validator on custom DropDown field - flutter

Question

I have mu custom DropDown Widget.
class DropDownMenuField extends StatefulWidget {
String title;
final InputDecoration decoration;
final String Function(String) validator;
final void Function(dynamic value) onSelectionDone;
final String initialValue;
final Color selectedItemColor;
final DropMenuMode menuMode;
int selectvalueindex;
final Function(String) onChanged;
var model;
DropDownMenuField(
{Key key,
this.title,
this.decoration,
this.validator,
this.onSelectionDone,
this.initialValue,
this.selectedItemColor,
this.model,
this.menuMode,
this.selectvalueindex,
this.onChanged})
: super(key: key);
#override
State<DropDownMenuField> createState() => _DropDownMenuFieldState();
}
class _DropDownMenuFieldState extends State<DropDownMenuField> {
final TextEditingController _controller = TextEditingController();
void _popUpModalBottomSheet(BuildContext context) async {
List<String> finalDataList = [];
List<dynamic> dataMap = await apiRegistrationDataList(widget.menuMode);
finalDataList = parseMap(dataMap);
final result = await showModalBottomSheet(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(9.0),
),
isScrollControlled: true,
context: context,
builder: (context) => DialogMenu(
title: widget.title,
data: finalDataList,
));
if (result == null) {
widget.title = widget.title;
_controller.text = widget.title;
} else {
// widget.title = result ?? widget.title;
// lab
labStyle = checkedLableStyle;
lable = result;
_controller.text = result;
widget.onSelectionDone(result);
widget.validator(result);
setState(() {});
}
SetGlobalRequaerData(result, dataMap);
}
#override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () => _popUpModalBottomSheet(context),
child: TextFormField(
controller: _controller,
readOnly: true,
enabled: false,
autovalidateMode: AutovalidateMode.onUserInteraction,
validator: widget.validator,
onChanged: widget.onChanged,
style: const TextStyle(
fontSize: 16,
color: Color(0xFF3C3C43),
),
decoration: InputDecoration(
labelStyle: labStyle,
hintStyle: TextStyle(
fontFamily: 'FiraSans',
color: GeneralStyles.greyColor,
),
fillColor: Colors.white,
filled: true,
contentPadding: const EdgeInsets.fromLTRB(16, 0, 0, 0),
errorStyle: const TextStyle(
color: Colors.red,
fontFamily: 'FiraSans',
fontWeight: FontWeight.w400,
fontSize: 13),
border: OutlineInputBorder(
borderRadius: const BorderRadius.all(Radius.circular(4)),
borderSide: BorderSide(
color: GeneralStyles.greyColor.withOpacity(0.5),
width: .5)),
enabledBorder: const OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(4)),
borderSide: BorderSide(color: Color(0xFF707070), width: .5)),
disabledBorder: OutlineInputBorder(
borderRadius: const BorderRadius.all(Radius.circular(4)),
borderSide:
BorderSide(color: GeneralStyles.greyColor, width: .5)),
focusedBorder: OutlineInputBorder(
borderRadius: const BorderRadius.all(Radius.circular(4)),
borderSide:
BorderSide(color: GeneralStyles.blackColor, width: 1)),
errorBorder: const OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(4)),
borderSide: BorderSide(color: Colors.red, width: .5),
),
labelText: lable,
hintText: widget.title,
suffixIcon: Icon(
Icons.keyboard_arrow_down,
color: GeneralStyles.greyColor,
),
),
));
}
}
And i call it on my registration page.
DropDownMenuField(
title: "Anrede",
model: widget.model,
menuMode: DropMenuMode.genders,
selectvalueindex: 0,
onSelectionDone: (value){
print(value);
},
validator: (value){
if(widget.model.selectedDropMenu[0].isEmpty){
return 'Bitte fülle das Feld aus';
}
return null;
},
),
When i click button when DropDownMenuField selectedValue is empty validator is work but when i select value widget don't call validator and don't change color from red. How call validator after change value. I read that when texteditingcontroller is changed, calling validator after him. i add it but not work.