validateCity method
Implementation
String? Function(String?) validateCity(String? value,
{String? requiredError, String? invalidError}) {
return (String? value) {
if (value == null || value.isEmpty) {
return requiredError ?? 'Please enter a city';
}
// Regular expression to validate city format
final cityRegex = RegExp(r'^[a-zA-Z ]+$');
if (!cityRegex.hasMatch(value)) {
return invalidError ?? 'Please enter a valid city';
}
return null; // Return null to indicate valid input
};
}