Create a validator in flutter

TextFormField(
  // The validator receives the text that the user has entered.
  validator: (value) {
    if (value.isEmpty) {
      return 'Please enter some text';
    }
    return null;
  },
);

Source: flutter.dev

Similar codes

2 votes178 views2 answers
Pass function as parameter in flutter
Dart
0 vote187 views1 answer
Flutter dropdown overflow
Dart
1 vote199 views1 answer
Transform widget flutter
Dart
0 vote218 views1 answer
Flutter stop while running app
Dart
0 vote172 views1 answer
Srring reverse dart
Dart
1 vote221 views1 answer
Convert iso date string into date and time string flutter
Dart
1 vote186 views2 answers
Flutter remove character from string
Dart
2 votes209 views2 answers
Flutter baseline
Dart
2 votes192 views1 answer
Flutter textfield with icon onclick
Dart
0 vote180 views1 answer
Random.secure dart
Dart