cf7

functions.php

<?php

wpcf7_add_form_tag( 'gens_raf_advance', 'wpcf7_wpgens_form_tag_handler',
		array(
			'url-attr' => true
		)
	);
  
  function wpcf7_wpgens_form_tag_handler( $tag ){
    $url = $tag['url'];
    
    $raf_user = new WPGens_RAF_User(get_current_user_id());
    $referralID = $raf_user->get_referral_id();
    $link = $url.'?raf='.$referralID;
    return '<input type="hidden" name="gens_raf" value="'.$link.'" />';
  }