validate method
Validate the value Return null if the value is valid Return the error message if the value is invalid Return null if the value is empty
Implementation
@override
String? validate() {
if (_value == null || _value?.trim().isEmpty == true) {
return null;
} else if (!RegExp(
r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]+@[a-zA-Z0-9]+\.[a-zA-Z]+")
.hasMatch(_value ?? '')) {
return message;
} else {
return null;
}
}