Custom Validation TextFormField Flutter - flutter

Question

I have Form and TextFormField inside it :
new Expanded(
child: TextFormField(
style: new TextStyle(color: Colors.white),
keyboardType: TextInputType.text,
validator: (String value) {
if (value.length <= 5) {
//Show error as a Snackbar
}
},
onSaved: (String value) {},
),
)
On a Buttom press I am checking if all the fields are validate :
if (_formKey.currentState.validate()) {
_submit();
}
Now the issue is when you call validate() and don't return any text in validate() method then it will consider it return true.
I don't want to show error below the textField but as a Snackbar.
Also, I tried setting an extra flag and setting in each validator Method but it gets complex if there are multiple fields in the form.
Can anyone tell me how can I handle this situation where _formKey.currentState.validate() should return false and validator method
inside TextFormField need not to return error text.

Answer 1

You shouldn't be using Form widget and TextFormField for displaying error in TextField.
Do validation by controllers instead
For Example
class MyHomePage extends StatefulWidget {
#override
MyHomePageState createState() {
return new MyHomePageState();
}
}
class MyHomePageState extends State<MyHomePage> {
final _text = TextEditingController();
bool _validate = false;
#override
void dispose() {
_text.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('TextField Demo'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('Error Showed if Field is Empty on Submit button Pressed'),
TextField(
controller: _text,
decoration: InputDecoration(
labelText: 'Enter the Value',
),
),
RaisedButton(
onPressed: () {
if(_text.text.length<=5){
// open dialog
}
},
child: Text('Submit'),
textColor: Colors.white,
color: Colors.blueAccent,
)
],
),
),
);
}
}