Flutter - TextField validation don't works - flutter

Question

What I need to do is when the onPressed is called, I get the Textfield error when I don't enter text.
class _ExampleDialogTextState extends State<ExampleDialogText> {
FocusNode focusNode = FocusNode();
final textController = TextEditingController();
bool noText = false;
String nameList = "";
#override
void initState() {
super.initState();
nameList = "";
focusNode.addListener(() {
if (!focusNode.hasFocus) {
setState(() {
noText = nameList.length == 0;
});
FocusScope.of(context).requestFocus(focusNode);
}
});
}
TextField(
focusNode: focusNode,
autofocus: true,
controller: textController,
style: TextStyle(
color: Colors.black, fontSize: 14),
decoration: InputDecoration(
counterText: '',
errorText:
noText ? 'Value Can\'t Be Empty' : null,)
RaisedButton(
onPressed: () {
setState(() {
nameList.isEmpty
? noText = true
: noText = false;
});
},)
}
But still, with that code it doesn't work for me. Attached here is the entire class
code
Thank you!

Answer 1

Your Code is correct but you can not update state in ShowDialog Widget, so you have to return Statetful Widget in ShowDialog.
I added whole code which i change.
import 'package:flutter/material.dart';
class Consts {
Consts._();
static const double padding = 16.0;
static const double buttonPadding = 5.0;
}
class DeleteWidget extends StatefulWidget {
const DeleteWidget({Key key}) : super(key: key);
#override
_DeleteWidgetState createState() => _DeleteWidgetState();
}
class _DeleteWidgetState extends State<DeleteWidget> {
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.blueAccent,
floatingActionButton: FloatingActionButton(
onPressed: () {
showDialogNameList();
},
backgroundColor: Colors.orange,
child: Icon(
Icons.add,
color: Colors.purple,
size: 40,
),
),
);
}
showDialogNameList() {
return showDialog(
context: context,
builder: (context) {
return CustomeDialog1();
});
}
}
class CustomeDialog1 extends StatefulWidget {
CustomeDialog1({Key key}) : super(key: key);
#override
_CustomeDialog1State createState() => _CustomeDialog1State();
}
class _CustomeDialog1State extends State<CustomeDialog1> {
FocusNode focusNode = FocusNode();
final textController = TextEditingController();
bool noText = false;
String nameList = "";
#override
void initState() {
super.initState();
nameList = "";
focusNode.addListener(() {
if (!focusNode.hasFocus) {
setState(() {
noText = nameList.length == 0;
});
FocusScope.of(context).requestFocus(focusNode);
}
});
}
#override
Widget build(BuildContext context) {
var screenHeight = MediaQuery.of(context).size.height;
return Dialog(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(Consts.padding),
),
elevation: 0.0,
child: Container(
height: screenHeight / 3,
child: Stack(
children: <Widget>[
Container(
padding: EdgeInsets.only(
top: Consts.padding,
bottom: Consts.padding,
left: Consts.padding,
right: Consts.padding,
),
margin: EdgeInsets.only(top: 0),
decoration: BoxDecoration(
color: Colors.white,
shape: BoxShape.rectangle,
borderRadius: BorderRadius.circular(Consts.padding),
boxShadow: [
BoxShadow(
color: Colors.black26,
blurRadius: 10.0,
offset: const Offset(0.0, 10.0),
),
],
),
child: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
TextField(
focusNode: focusNode,
autofocus: true,
controller: textController,
cursorColor: Colors.white,
style: TextStyle(color: Colors.black, fontSize: 14),
decoration: InputDecoration(
counterText: '',
errorText: noText ? 'Value Can\'t Be Empty' : null,
hintText: 'List Name',
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.black),
),
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.green),
),
labelStyle: TextStyle(
color: Colors.white, fontWeight: FontWeight.bold),
),
onChanged: (String text) {
nameList = text;
},
),
Padding(
padding: const EdgeInsets.all(8.0),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Container(
width: 150.0,
height: 45.0,
child: RaisedButton(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10),
),
onPressed: () {
setState(() {
nameList.isEmpty
? noText = true
: noText = false;
});
},
padding:
EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 0.0),
color: Color(0xFF2DA771),
child: Text('Add',
style: TextStyle(
color: Colors.white,
fontFamily: 'Roboto',
fontSize: 16)),
),
),
],
),
)
],
),
),
)
],
),
));
}
}