More $_GET vars via snippet?

<?php
/*   GET_test
     usage: add the snippet call to the document content
     [!Get_test!]
     
*/
// set seperator placeholder
$seperator = ($modx->config['friendly_urls'] =="1") ? "?" : "&";
$modx->setPlaceholder('url_sep', $seperator);  // [+url_sep+]


$this_doc = $modx->documentObject['id'];
$modx->setPlaceholder('this_doc', $this_doc);  // [+this_doc+]

// set up the output
$output ='';

// check for $_GET[''] and set variables accordingly
// NOTE THAT THIS DOES NOT HAVE ANY SECURITY CHECKING SO THAT PART IS UP TO YOU
$get_item1 = isset($_GET['get_item1']) ? $_GET['get_item1'] : '';
$get_item2 = isset($_GET['get_item2']) ? $_GET['get_item2'] : '';
$get_item3 = isset($_GET['get_item3']) ? $_GET['get_item3'] : '';

// print a link to this page 
$output .='<p><a href="[~[+this_doc+]~][+url_sep+]get_item1=Value 1&get_item2=Value 2&get_item3=Value 3"></p>';

// print the results
$output .='<p>Value 1: '.$get_item1.'<br>
              Value 2: '.$get_item2.'<br>
              Value 3: '.$get_item3.'</p>';

return $output;
?>

// check for $_GET[''] and set variables accordingly
$get_item1 = isset($_GET['get_item1']) ? $_GET['get_item1'] : '';
$get_item2 = isset($_GET['get_item2']) ? $_GET['get_item2'] : '';
$get_item3 = isset($_GET['get_item3']) ? $_GET['get_item3'] : '';

function sanitize_string($string, $min='', $max=''){
	// strip bad characters
	$string = preg_replace("/[^\w-]/", "", $string);
	$len = strlen($string);
	// check length
	if((($min != '') && ($len < $min)) || (($max != '') && ($len > $max))) {
		return FALSE;
	}
  	return $string;
}

//string
$var = filter_var($var, FILTER_SANITIZE_STRING);

// int
$int_options = array("options"=>array("min_range"=>0, "max_range"=>256));
$var = filter_var($var, FILTER_VALIDATE_INT, $int_options);

<?php
 // set seperator placeholder
$seperator = ($modx->config['friendly_urls'] =="1") ? "?" : "&";
$modx->setPlaceholder('url_sep', $seperator);  // [+url_sep+]


$this_doc_id = $modx->documentObject['id'];
$modx->setPlaceholder('this_doc_id', $this_doc_id);  // [+this_doc_id+]

if (!function_exists(sanitize)){
function sanitize($value, $type='', $min='', $max=''){
    $type =isset($type) ? $type : '';
    if($type ==''){
        $value='No type sent';
        return $value;
    }

    $allowed_array =array('string', 'integer');
    if(!empty($type) && !in_array($type, $allowed_array)){
        $value='Type not allowed';
        return $value;
    }else{
        switch($type){
            case '': $value='Type value is empty';
              return $value;
            break;

            case 'string';
              // strip bad characters
              $value = preg_replace("/[^\w-]/", "", $value);
              $len = strlen($value);
              // check length
              if((($min != '') && ($len < $min)) || (($max != '') && ($len > $max))) {
                      //return FALSE;
                      $value='Character params were not correct';
              }
              return $value;
            break;

            case 'integer':
              $value = intval($value);
              if((($min != '') && ($value < $min)) || (($max != '') && ($value > $max))) {
                      //return FALSE;
                      $value='Wrong criteria, min value of '.$min.' and max value of '.$max.' required';
              }
              return $value;
            break;

            // add more checks here
            // case '': ''; break;

            default: '';
        return;
        }
    }
}
}

// set up the output
$output ='';

// check for $_GET[''] and set variables accordingly
$get_item1 = isset($_GET['get_item1']) ? sanitize($_GET['get_item1'], $type='string') : '';
$get_item2 = isset($_GET['get_item2']) ? sanitize($_GET['get_item2'], $type='integer', $min='3', $max='20') : '';
$get_item3 = isset($_GET['get_item3']) ? sanitize($_GET['get_item3'], $type='wrong') : 'Empty value';
$get_item4 = isset($_GET['get_item4']) ? sanitize($_GET['get_item4'], $type='string') : '';
$get_item5 = isset($_GET['get_item5']) ? sanitize($_GET['get_item5'], $type='integer', $min='2', $max='50') : '';
$get_item6 = isset($_GET['get_item6']) ? sanitize($_GET['get_item6'], $type='wrong') : 'Empty value';

// print links to this page with various criteria
$output .='<p>
<ul>
<li><a href="[~[+this_doc_id+]~][+url_sep+]get_item1=Value 1&get_item2=5">[~[+this_doc_id+]~][+url_sep+]get_item1=Value 1&get_item2=5</a></li>
<li><a href="[~[+this_doc_id+]~][+url_sep+]get_item1=B&A)#D Character+@S&get_item2=25">[~[+this_doc_id+]~][+url_sep+]get_item1=B&A)#D Character+@S&get_item2=25</a></li>
<li><a href="[~[+this_doc_id+]~][+url_sep+]get_item1=me@<supposed to be an AT sign>myemail.com&get_item2=12&get_item3=20^JRE">[~[+this_doc_id+]~][+url_sep+]get_item1=me@<supposed to be an AT sign>myemail.com&get_item2=12&get_item3=20^JRE</a></li>
<li><a href="[~[+this_doc_id+]~][+url_sep+]get_item4=Value 1&get_item5=5&get_item6=5">[~[+this_doc_id+]~][+url_sep+]get_item4=Value 1&get_item5=5&get_item6=5</a></li>
</ul>
</p>';

// print the results
$output .='<p>Value 1: '.$get_item1.'<br>
              Value 2: '.$get_item2.'<br>
              Value 3: '.$get_item3.'</p>';
              
$output .='<p>Value 4: '.$get_item4.'<br>
              Value 5: '.$get_item5.'<br>
              Value 6: '.$get_item6.'</p>';


return $output;
?>

# For product-detail-pages
RewriteRule ^product/(.*)/(.*)/(.*)/(.*)/(.*)/(.*)/(.*).html$ productdetails.html?p1=$1&p2=$2&p3=$3&p4=$4&p5=$5&p6=$6 [L,QSA]
RewriteRule ^product/(.*)/(.*)/(.*)/(.*)/(.*).html$ productdetails.html?p1=$1&p2=$2&p3=$3&p4=$4 [L,QSA]
RewriteRule ^product/(.*)/(.*)/(.*).html$ productdetails.html?p1=$1&p2=$2 [L,QSA]

# For Friendly URLs
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?q=$1 [L,QSA]