Cookie array with strings returns false - php

Question

I'm trying to add the current page's URL to a cookie called '$visitedPages'. For reference, the Wordpress function 'get_permalink()' returns the URL.
In the below, the var_dump returns 'false'. Whereas if I replace 'get_permalink()' on line 2 with 'get_the_ID()', which returns the integer page IDs, this all works just fine.
I tried stripping special characters from the url, but it still returns 'false', so I suspect this problem is something to do with decoding strings from the cookie.
// define the new value to add to the cookie
$currentPage = get_the_permalink(get_the_ID());
// if the cookie exists, read it and unserialize it. If not, create a blank array
if(isset($_COOKIE['visitedPages'])) {
$visitedPagesSerialised = $_COOKIE['visitedPages'];
$visitedPages = unserialize($visitedPagesSerialised)
var_dump($visitedPages);
} else {
$visitedPages = array();
}
// add the current page id to the array and serialize
$visitedPages[] = $currentPage;
$newCookieSerialized = serialize($visitedPages);
// save the cookie for 30 days
setcookie('visitedPages', $newCookieSerialized, time() + (86400 * 30), "/");
?>

Answer 1

Try getting the ID, and adding it in to the permalink function. I'm assuming when you say you used get_the_ID() it means you are replacing permalink function with get ID function. Try using them in tandem.
$page_ID = get_the_ID();
$currentPage = get_the_permalink($page_ID);

Answer 2

I needed to remove escaped quotes from the cookie with stripslashes() before the json_decode. Why json_decode doesn't do this itself, I have no idea.
Here is the working code. Note: it is better to use exactly the same code but with json_encode() and json_decode() instead of serialize() and unserialize() so I've changed that too, but the principle is the same.
// define the new value to add to the cookie
$currentPage = get_the_permalink(get_the_ID());
// if the cookie exists, read it and unserialize it. If not, create a blank array
if(isset($_COOKIE['visitedPages'])) {
$visitedPagesSerialised = stripslashes($_COOKIE['visitedPages']);
$visitedPages = json_decode($visitedPagesSerialised)
var_dump($visitedPages);
} else {
$visitedPages = array();
}
// add the current page id to the array and serialize
$visitedPages[] = $currentPage;
$newCookieSerialized = json_encode($visitedPages);
// save the cookie for 30 days
setcookie('visitedPages', $newCookieSerialized, time() + (86400 * 30), "/");