help displaying cart contents in a web store

[phpnj1]

Hi,

 

I'm working on a mock web store for a school project. I'm stuck trying to get my cart to display right. I've been following/editing a tutorial I found online but I keep getting this error:  Warning: extract() expects parameter 1 to be array, boolean given in C:\xampp\htdocs\inc\functions.inc.php on line 29

 

here is the entire showCart function. any ideas what's causing this? Thanks in advance.

 

function showCart() {
global $db;
$cart = $_SESSION['cart'];
if ($cart) {
	$items = explode(',',$cart);
	$contents = array();
	foreach ($items as $item) {
		$contents[$item] = (isset($contents[$item])) ? $contents[$item] + 1 : 1;
	}
	$output[] = '<form action="cart.php?action=update" method="post" id="cart">';
	$output[] = '<table>';
	foreach ($contents as $id=>$qty) {
		$sql = 'SELECT * FROM inventory WHERE productID = '.$id;
		$result = $db->query($sql);
		$row = $result->fetch();
		extract($row);
		$output[] = '<tr>';
		$output[] = '<td><a href="cart.php?action=delete&id='.$id.'" class="r">Remove</a></td>';
		$output[] = '<td>'.$title.' by '.$author.'</td>';
		$output[] = '<td>$'.$price.'</td>';
		$output[] = '<td><input type="text" name="qty'.$id.'" value="'.$qty.'" size="3" maxlength="3" /></td>';
		$output[] = '<td>$'.($price * $qty).'</td>';
		$total += $price * $qty;
		$output[] = '</tr>';
	}
	$output[] = '</table>';
	$output[] = '<p>Grand total: <strong>$'.$total.'</strong></p>';
	$output[] = '<div><button type="submit">Update cart</button></div>';
	$output[] = '</form>';
} else {
	$output[] = '<p>You shopping cart is empty.</p>';
}
return join('',$output);
}