Show/hide page content based on cookie from url parameter - php

Question

I am looking to show some content on a page based on the parameter in a link.
If a link is given to a user https://www.examplesite.com/example-page/?client_feeback=1
then they will see the content of the page, if not using the link, then users will not see the content.
Additionally, I need the users of the link to be able to look on other pages and return to the page where the content is hidden/shown and still see the content.
I have set a cookie in functions.php, that will expire in 30days.
code added into functions.php
add_action('init', 'set_feedback_cookie');
function set_feedback_cookie () {
$name = 'client_feedback';
$value= 1;
setcookie($name, $value, strtotime( '+30 days' ), "/example-page/", "examplesite.com", "true" );
}
I have then added the following into the example-page.php template file
<?php
if (!isset($_GET['client_feedback'])) { ?>
<style type="text/css">#form__feedback {display:none!important}</style>
<?php } else { ?>
<style type="text/css">#form__feedback {display:block!important}</style>
<?php } ?>
The cookie is loaded on to the site and the content is hidden/shown when using/ not-using the url link.
What is not working, is the ability to browse other pages on the site and come back to the page with the hidden content and still see it!

Answer 1

Since you confirmed in the comment section that you are not leaving your own domain, You could put the GET variable into a SESSION variable and do your checks based on that. That way, you will always have that available to you until the user leaves the site or you manually kill the session somewhere.
Example:
<?php
session_start();
$_SESSION["client_feedback"] = $_GET['client_feedback'];
?>
As long as declare your session_start(); at the very beginning of your page(s) (literally before ANYTHING else), you can access your session variable anywhere you want.
Now you can perform checks on your session variable with the logic you're trying to achieve in order to display your desired content.
Full Example:
<?php
session_start();
if($_GET['client_feedback'] != "") {
$_SESSION["client_feedback"] = $_GET['client_feedback'];
}
if( isset( $_SESSION["client_feedback"] ) != "" ) {
?> <style type="text/css">#form__feedback {display:block!important}</style> <?php
} else {
?> <style type="text/css">#form__feedback {display:none!important}</style> <?php
}
?>
You can read more about PHP sessions here.