Reply To: Limit field value to letters only with no numbers

• John Huebner

• June 15, 2020 at 10:45 pm

https://www.advancedcustomfields.com/resources/acf-validate_value/

add_filter('acf/validate_value/name=your-field-name', 'allow_only_letters', 20, 3);
function allow_only_letters($valid, $value, $field, $input) {
  if (!$valid) {
    return $valid;
  }
  if (preg_match('/[^a-z]/i', $value)) {
    return 'enter only letters';
  }
  return $valid;
}