Changing values

I second this request and have changed the category to 'task'.

By default, the Link module will add the 'http://' if it is missing. This makes it more user friendly for average folks. I think 'Field validation', which does great things for admins, should build on this simple expectation and do the same.

The 'Link' module does it this way. Would this work for 'Field validation' ?

/**
 * Forms a valid URL if possible from an entered address.
 * 
 * Trims whitespace and automatically adds an http:// to addresses without a
 * protocol specified
 *
 * @param string $url
 * @param string $protocol
 *   The protocol to be prepended to the url if one is not specified
 */
function link_cleanup_url($url, $protocol = 'http') {
  $url = trim($url);
  $type = link_validate_url($url);

  if ($type === LINK_EXTERNAL) {
    // Check if there is no protocol specified.
    $protocol_match = preg_match("/^([a-z0-9][a-z0-9\.\-_]*:\/\/)/i", $url);
    if (empty($protocol_match)) {
      // But should there be? Add an automatic http:// if it starts with a domain name.
      $LINK_DOMAINS = _link_domains();
      $domain_match = preg_match('/^(([a-z0-9]([a-z0-9\-_]*\.)+)(' . $LINK_DOMAINS . '|[a-z]{2}))/i', $url);
      if (!empty($domain_match)) {
        $url = $protocol . "://" . $url;
      }
    }
  }

  return $url;
}

It seems that we could not change field value in hook_field_attach_validate.
Maybe we could change it in other hooks.