Php new cookie overwrites the previous - php

Question

In a webshop product page, i am sending the product id with ajax to this php file:
<?php
include_once("connect.php");
if(isset($_POST['product_id']))
{
$product_id = mysqli_real_escape_string($kapcs, $_POST['product_id']);
$cookie_name = "kedvenc_termek";
$cookie_value = $product_id;
setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/");
echo 'Saved to the favorit products.';
}
?>
My problem is, that when i have id-s in the kedvenc_termek cookie, and i want to add another product id as favorit product, the new cookie value will overwrite the value in the cookie.
For example, if i have 179 stored in the cookie, and i add the 180 product id to it, the cookie value will be 180, and not 179,180.

Answer 1

You're overwriting the value every time. So you need to append the value, not overwrite it
$cookie_name = "kedvenc_termek";
$cookie_value = '';
if(isset($_COOKIE[$cookie_name])) {
$cookie_value = $_COOKIE[$cookie_name] . ',';
}
$cookie_value .= $product_id;
setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/");

Answer 2

You need to use an array to save the data. You can use PHP's serialize() method to save array data as a string, and use unserialize() to read the data. Try this:
<?php
include_once("connect.php");
if(isset($_POST['product_id']) && is_int($_POST['product_id'])) {
$product_id = $_POST['product_id'];
$cookie_name = "kedvenc_termek";
$data = unserialize($_COOKIE[$cookie_name]);
if(!in_array($product_id, $data)) {
$data[] = $product_id;
}
setcookie($cookie_name, serialize($data), time() + (86400 * 30), "/");
echo 'Saved to the favorite products.';
}
?>