Shopping cart not displaying products, intval?

Question

I am creating a PHP shopping cart linked to SQL database, from a tutorial i am following.

The code below SHOULD display all my products, however I believe that the

$id = intval($_GET['id']);

section is messing it up. The SKU's of the products are Varchar, not integers, so I am lead to believe that this is causing the problem with "intval". Is there another datatype I can insert that will display my products again?

<?php

if (isset($_GET['action']) && $_GET['action'] == "add")
{
    $id = intval($_GET['id']);

    if(isset($_SESSION['cart'][$id]))
    {
        $_SESSION['cart'][$id]['quantity']++;
    } 
    else 
    {
        $sql2   = "SELECT * FROM products WHERE SKU={$id}";
        $query2 = mysql_query($sql2);

        if(mysql_num_rows($query2) != 0)
        {
            $row2 = mysql_fetch_array($query2);
            $_SESSION['cart'][$row2['SKU']] = array("quantity => 1, "price" => $row['price']);

        } 
        else 
        {
            $message = "This product id is invalid";
        }
    }
}
?>
<h2 class="message"><?php if(isset($message)){echo $message; ?></h2>
<h1>Product Page</h1>
<table>
    <tr>
        <th>Name</th>
        <th>Description</th>
        <th>Price</th>
        <th>Action</th>
    </tr>

    <?php
    $sql   = "SELECT * FROM products ORDER BY SKU ASC";
    $query = mysql_query($sql)or die(mysql_error());

    while($row = mysql_fetch_assoc($query))
    {
        ?>
        <tr>
            <td><?php echo $row['name']; ?></td>
            <td><?php echo $row['Description']; ?></td>
            <td><?php echo "£" . $row['price']; ?></td>
            <td><a href="index.php?page=products&action=add&id=<?php echo $row['SKU']; ?>">Add to Cart</a></td>
        </tr>

        <?php
    }
    ?>

</table>

You should use prepared statements with PDO or mysqli instead of injecting variables in your sql statements. — jeroen, Jun 11 '13 at 19:00
You have a syntax error: `"quantity => 1,` must be `"quantity" => 1,`. You forgot a double quote — Agustin Meriles, Jun 11 '13 at 19:01
PHP makes very little distinction between numbers and strings. There are many things wrong with this code. It doesn't follow many of the modern good practices. This tutorial is kinda bad. I honestly can't tell you what this code does, it's too messy. — Halcyon, Jun 11 '13 at 19:01
*Are* the product IDs integers? PHP doesn't care how your column type is defined it only cares what's in it. Show us your DB table structure. — Madbreaks, Jun 11 '13 at 19:03
my product IDs are test1, test2, test3 Unrealistic I know, but for the task they must remain strings — WibblyWobbly, Jun 11 '13 at 19:04

score 1 · Answer 1 · answered Jun 11 '13 at 19:01

1

You are missing an ending quote here:

$_SESSION['cart'][$row2['SKU']] = array("quantity" => 1, "price" => $row['price']);

You're also missing a } sign

<h2 class="message"><?php if(isset($message)){echo $message; } ?> </h2>

answered Jun 11 '13 at 19:01

Martin

410
2
11

Hi, I have added the quote after quantity, yet still no products are displayed – WibblyWobbly Jun 11 '13 at 19:02

score 0 · Accepted Answer · edited May 23 '17 at 12:18

0

Check the docs for intval() and you'll see that this method returns 0 when the variable isn't an integer.

if you're looking to search for this, you can just change the line to:

$id = $_GET['id'];

to get the variable as a string

However there are two things to bear in mind with this:

This is liable to lead to sql injection vulnerabilities if not treated properly in your code
The mysql_ functions are deprecated, and shouldn't be used in new code... there're a number of good tutorials and debates on the matter... use PDO or mysqli

edited May 23 '17 at 12:18

Community

1
1

answered Jun 11 '13 at 19:04

msturdy

10,479
11
41
52

I have changed this section to what you suggested and it displays my products again. However, it displays the $message "This product id is invalid" – WibblyWobbly Jun 11 '13 at 19:08
what's in your DB? is there actually an ID that matches your products? – msturdy Jun 11 '13 at 19:16
The DB only holds SKU, Name, Description and price. The 3 products all have the sku (test1, test2,test3) – WibblyWobbly Jun 11 '13 at 19:19
And what are you passing to the page as the $_GET variables? – msturdy Jun 11 '13 at 19:32
I'm trying to pass the SKU values – WibblyWobbly Jun 11 '13 at 19:35

Shopping cart not displaying products, intval?

2 Answers2