How to update variable from TextFormField in flutter? - flutter

Question

I have TextFormField which has its own controller. I also have a disabled button that I would like to enable after any input inside TextFormField. The problem is that I managed to enable the button however only when I close the keyboard. For example, if I'm typing a word in a session it won't enable the button unless I close the keyboard. I would like to enable the button after the first character.
This is the code:
final TextEditingController passwordController = new TextEditingController();
TextFormField(
keyboardType: TextInputType.visiblePassword,
controller: passwordController,
),
RaisedButton(
onPressed: (passwordController.text== "") ? null : () {
setState(() {
_isLoading = true;
});
signIn(email, passwordController.text);
},
),

Answer 1

Is this what you're looking for?
final TextEditingController _controller = TextEditingController();
bool _isLoading = true;
// it tracks if TextField is enabled or disabled
bool _enabled = false;
#override
void initState() {
super.initState();
_controller.addListener(() { // you need to add listener like this
setState(() {
if (_controller.text.length > 0)
_enabled = true;
else
_enabled = false;
});
});
}
Widget build(context) {
return Scaffold(
body: Column(
children: <Widget>[
SizedBox(height: 50),
TextFormField(controller: _controller),
RaisedButton(
onPressed: !_enabled ? null : () => setState(() => _isLoading = true),
),
],
),
);
}

Answer 2

Based on what you're looking for, I created a boolean called isEnabled and set the initial value to false. This should work for you!
bool isEnabled;
final TextEditingController passwordController = new TextEditingController();
#override
void initState() {
super.initState();
passwordController.addListener(() {
setState(() {
if (passwordController.text.length > 0) {
isEnabled = true;
} else {
isEnabled = false;
}
});
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: <Widget>[
TextFormField(
keyboardType: TextInputType.visiblePassword,
controller: passwordController,
),
RaisedButton(
child: Text('Click Me'),
onPressed: isEnabled ? () {
//print('Button has been pressed');
setState(() {
_isLoading = true;
});
signIn(email, passwordController.text);
} : null,
),
],
),
);
}

Answer 3

This worked:
var password = '';
TextFormField(
keyboardType: TextInputType.visiblePassword,
controller: passwordController,
onChanged: (value){
setState(() {
password = value;
});
},
),
RaisedButton(
onPressed: (password == "") ? null : () {
setState(() {
_isLoading = true;
});
signIn(email, password);
},
),