First, which version of modx are you using... Evolution or Revolution?
If Evolution, maybe something like this - create a new snippet with the code below:
<?php
/* url_fullname_param
usage:
<a hre="link_to_form.html[!url_fullname_param!]">Form Link</a >
with furls:
<a hre="link_to_form.html?default=FullName">Form Link</a >
without furls:
<a hre="index.php?id=XX&default=FullName">Form Link</a >
*/
// modify to reflect your field name
$param_name ='default';
$output ='';
if(isset($_SESSION['webFullname'])){
$url_sep = $modx->config['friendly_urls'] =='1' ? '?' : '&';
$fullname = str_replace(" ", "_",$_SESSION['webFullname']);
$output .= $url_sep . $param_name . '=' . $fullname;
return $output;
}
?>
Then add the snippet to the link that goes to the form.
You may also need to add it to the action part of the form itself if you need to keep it persistant, something like this:
action="form_action.html[!url_fullname_param!]"
