Flutter's Form + TextFormField handle input and validation cleanly.
final _formKey = GlobalKey<FormState>();
Form(
key: _formKey,
child: Column(children: [
TextFormField(
decoration: InputDecoration(labelText: 'Email'),
validator: (v) => (v == null || !v.contains('@')) ? 'Invalid email' : null,
),
ElevatedButton(
onPressed: () {
if (_formKey.currentState!.validate()) {
// all fields valid — submit
}
},
child: Text('Submit'),
),
]),
)Tip: Return
null from a validator when the value is valid, or an error string when it isn't.Summary
Wrap fields in a Form with a GlobalKey, validate each TextFormField, and submit only when validate() passes.