Shopping cart deletes all quantities instead of one

Question

I'm attempting to create a simple shopping cart in PHP. I have managed to add items to a session. If you add the same item the quantity updates.

However when I delete an item that has a quantity of more than 1 it will delete everything for that item rather than taking away 1 from the quantity.

I'm wondering if anyone could check what I might be doing wrong?

Takes the ID of the product:

<a href="checkout.php?id=<?php echo $earthProducts -> id; ?>"> Order Now </a>

I have an Item class:

<?php
Class Item{
var $id;
var $name;
var $price;
var $quantity;
}
?>

On the checkout page it will display all products that are currently in the cart:

require 'item.php';

    if (isset($_GET['id'])) {
        $result = mysqli_query($con, 'SELECT * FROM earthProducts WHERE id=' . $_GET['id']);
        $earthProducts = mysqli_fetch_object($result);
        $item = new Item();
        $item->id = $earthProducts->id;
        $item->name = $earthProducts->name;
        $item->price = $earthProducts->price;
        $item->quantity = 1;

        // Check product is existing in cart
        $index = -1;
        $cart = unserialize(serialize($_SESSION['cart']));
        for ($i = 0; $i < count($cart); $i++)
            if ($cart[$i]->id == $_GET['id']) {
                $index = $i;
                break;
            }
        if ($index == -1) {
            $_SESSION['cart'] [] = $item;
        } else {
            $cart[$index]->quantity++;
            $_SESSION['cart'] = $cart;
        }
    }
    ?>

I then print the cart with a button to delete that item:

<table cellpadding="2" cellspacing="2" border="1">
                    <tr>
                        <th>Option</th>
                        <th>Id</th>
                        <th>Name</th>
                        <th>Price</th>
                        <th>Quantity</th>
                        <th>Sub Total</th>
                    </tr>
                    <?php
                    $cart = unserialize(serialize($_SESSION['cart']));
                    $s = 0;
                    $index = 0;
                    for ($i = 0; $i < count($cart); $i++) {
                        $s += $cart[$i]->price * $cart[$i]->quantity;
                        ?>
                        <tr>
                            <td> <a href="checkout.php?index=<?php echo $index; ?>" onclick="return confirm('Are you sure?')">Delete</td>
                            <td><?php echo $cart[$i]->id; ?></td>
                            <td><?php echo $cart[$i]->name; ?></td>
                            <td><?php echo $cart[$i]->price; ?></td>
                            <td><?php echo $cart[$i]->quantity; ?></td>
                            <td><?php echo $cart[$i]->price * $cart[$i]->quantity; ?></td>
                        </tr>
                        <?php
                        $index++;
                    }
                    ?>
                    <tr>
                        <td colspan="4" align="right">Sum</tr>
                    <td align="left"> <?php echo $s ?></td>
                </table>
                <br>
                <a href="earth_products.php"> Continue Shopping </a>

                <br>
                <br>
                <?php
                print_r($cart);
                ?>

My code to delete an item in the cart (Which is wrong):

// Delete product in cart
    if (isset($_GET['index'])) {
        $cart = unserialize(serialize($_SESSION['cart']));
        unset($cart[$_GET['index']]);
        $cart = array_values($cart);
        $_SESSION['cart'] = $cart;
    }

So if I have item-1 with quantity of 1, I press delete which will remove it. If I have item-2 with a quantity of 2 it will delete both quantities and remove item-2 from the cart.

Thank you in advance if anyone can assist with this.

Answer 1

You need to check quantity before unsetting, Something like this should work:

if (isset($_GET['index'])) {
    $cart = unserialize(serialize($_SESSION['cart']));
    if ($cart[$_GET['index']]->quantity == 1){
       unset($cart[$_GET['index']]);
    }else{
       $cart[$_GET['index']]->quantity--;
    }
    $cart = array_values($cart);
    $_SESSION['cart'] = $cart;
}