code: protected function fieldShouldNotBeSaved($field, $value, $selectedFields)
      {
          return (!empty($selectedFields) && !in_array($field, $selectedFields)) || $field === 'ID';
      }
docs: Determine whether the field should be stopped from passing to "update".
  
  @param string $field
  @param mixed  $value
  @param array  $selectedFields
  
  @return bool