PHP MySQL Shopping Cart - Adding items to session - php

Question

I am practicing with PHP, and as a result, I ended up creating a dummy online store. I managed to implement most of the online functionality, but I am struggling with the shopping cart.
Once the user logs in and enters the product area of the site, I want the user to be able to add items to a cart. I have been following a phpAcademy YouTube tutorial. I've managed to display all the products with an add button/hyperlink to link each product to a processing page called cart.php. Each button's link matches their associated product ID.
When I test this and click "add", the ID of the product does not appear on the cart.php page.
user_man_boxing_gloves.php:
<?php
session_start();
include('connect_mysql.php');
$product_name = 'product_name';
$product_qua = 'product_qua';
$product_price = 'product_price';
$product_image = 'product_image';
$product_des = 'product_des';
$get = mysql_query("SELECT product_id, product_image, product_name, product_des, product_price, product_type FROM products WHERE product_type='ManGloves' AND product_qua > 0 ORDER BY product_id DESC");
if(mysql_num_rows($get) == 0)
{
echo "There are no Products to display";
}
else
{
?>
<?php
while($get_row = mysql_fetch_assoc($get))
{
?>
<table id='display'>
<tr><td><?php echo "<img src=$get_row[$product_image] class='grow'>" ?></td></tr>
<tr>
<th></th>
<th><strong>Avalible</strong></th>
<th><strong>Price</strong></th>
<th><strong>Description</strong></th>
</tr>
<tr>
<td width='290px'><?php echo "$get_row[$product_name]" ?></td>
<td width='290px'><?php echo "$get_row[$product_qua]" ?></td>
<td width='290px'><?php echo "$get_row[$product_price]" ?></td>
<td width='290px'><?php echo "$get_row[$product_des]" ?></td>
</tr>
<tr>
<td><?php echo 'Add'; ?></td>
</tr>
</table>
<?php
}
}
?>
cart.php:
<?php
if(isset($_GET['add'])){
$_SESSION['cart_'.$_GET['add']]+='1';
}
echo $_SESSION['cart_'];
?>
I want to display the product ID to see if my code works, and I want to do further processing after verifying that it works.
Looking at the screenshot, it appears that the add button correctly shows the product ID.

Answer 1

It looks like the issue in cart.php deals with the following snippet:
if(isset($_GET['add'])){
$_SESSION['cart_'.$_GET['add']]+='1';
}
Working this out, this would mean that with an ID of 1, you could see the following in your session array:
$_SESSION['cart_1'] = 1;
$_SESSION['cart_2'] = 4;
What you probably want, for the display, is to store an array into cart. That is,
if(isset($_SESSION['cart']))
{
$arr = unserialize($_SESSION['cart']);
}
else
{
$arr = array();
}
if(isset($_GET['add'])){
$arr[$_GET['add']] += 1;
}
$_SESSION['cart'] = serialize($arr);
var_dump(unserialize($_SESSION['cart']));