Bug in Shopping Cart Array

**owentech** · Nov 17, 2009 09:51

Hi,
I have the following shopping cart that works perfectly on my home PC.

Code:

<?php
// start session
session_start();
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>my title</title>
<link href="css/style.css" rel="stylesheet" type="text/css" />
</head>

<body>
<center>
<table align="center" class="maintable">
<tr>
<td colspan="2">
    <!--Top Block Starts -->
    <?php include('inctop.php'); ?>
    <!--Top Block Ends -->
</td>
</tr>		

<!--Left Block Starts -->	
<tr>
<td class="blk2_lp" width="30%" valign="top">                    
    <?php include('inccategories.php'); ?>
</td>
<!--Left Block Ends -->
        
<!--Right Block Starts -->
<td valign="top">
<span class="wel">Your Shopping Cart</span><br><br>
    <?php
        include('[path to connection file].php');
        if ($_GET['itemtoadd'])
        {
            $itemtoadd = $_GET['itemtoadd'];
            $_SESSION['shoppingcart'][$itemtoadd] = 1;
        }
        if ($_GET['itemtoremove'])
        {
            $itemtoremove = $_GET['itemtoremove'];
            unset($_SESSION['shoppingcart'][$itemtoremove]);
        }
        if (isset($_POST['cmdupdatecart'])) 
        {
            foreach ($_POST['user_qty'] as $cartitem => $newqty) 
            {
                if ( $newqty== 0 ) 
                {
                    unset ($_SESSION['shoppingcart'][$cartitem]);
                } 
                elseif ( $newqty > 0 ) 
                {
                    $_SESSION['shoppingcart'][$cartitem] = $newqty;
                }
                next($_POST['user_qty']);
            }
        }       
        $mycart = $_SESSION['shoppingcart'];
        echo "<form action ='shoppingcart.php' method ='post'>";
        echo "<table ALIGN=\"center\" WIDTH=\"90%\" class=\"noborders\">";
        if (is_array($mycart))
        {
            echo "<TR class=\"header\">";
            echo "<TD width = \"5%\">&nbsp;</td>";
            echo "<TD width = \"20%\">&nbsp;</td>";
            echo "<TD width = \"35%\"><B>Item</B></font>&nbsp;</td>";
            echo "<TD width = \"10%\">Unit Price</td>";
            echo "<TD width = \"10%\">Quantity</td>";
            echo "<TD width = \"10%\">Total Price</td>";
            echo "<TD width = \"10%\">Remove</td>";
            echo "</TR>";
            $dbconnection = mysql_connect($dbhost,$dbusername,$dbpassword);
            mysql_select_db($database,$dbconnection );
            $counter = 1;
            $totalprice = 0;
            foreach ($mycart as $itemqty) 
            {
                $cartitemid = key($mycart);
                $sql = "SELECT * FROM tblitems WHERE itemid = $cartitemid";
                $result = mysql_query($sql,$dbconnection) or die(mysql_error());
                $myrow = mysql_fetch_array($result);
                $itemid = $myrow['itemid'];
                $itemname = $myrow["itemname"];
                $itemprice = $myrow["itemprice"];
                $itemtotalprice = $itemprice * $itemqty;
                $itempicturename = (empty($myrow["itempicture"])) ? 'default.jpg' : $myrow["itempicture"];
                $itempicture = "<img src=\"demo/itempics/$itempicturename\" width=\"100\" height=\"100\">";
                $mysubcategoryidf = $myrow["subcategoryidf"];
                $subcategoryname = getsubcategoryname($mysubcategoryidf);
                if($counter %  2) {
                    echo "<TR>";
                } else {
                    echo "<TR bgcolor=\"#CCCCCC\">\n";
                }//colour has now been set :-)
                echo "<TD>$counter</td>";
                echo "<TD>$itempicture</td>";
                echo "<TD>$itemname</td>";
                echo "<TD align='right'>".number_format($itemprice,2)."</td>";
                echo "<TD align='right'><input size='4' type='text' name=\"user_qty[".$itemid."]\" value='$itemqty'></td>";
                //echo "<TD>$itemqty</td>";
                echo "<TD align='right'>".number_format($itemtotalprice,2)."</td>";
                echo "<TD><a href=\"shoppingcart.php?itemtoremove=$itemid\">Remove</a></td>";
                echo "</tr>";
                $counter = $counter + 1;
                $totalprice = $totalprice + $itemtotalprice;
                next($mycart);
            }
            echo "<tr class=\"header\">";
            echo "<td colspan='5' align='right'>Your Total Price is:</td>";
            echo "<td align='right'><b>".number_format($totalprice,2)."</b></td>";
            echo "<td>&nbsp;</td>";
            echo "</tr>";
            
            echo "<tr>";
            echo "<td colspan='5' align='right'>Update Cart</td>";
            echo "<td align='right'><input name=\"cmdupdatecart\" value=\"Update\" type=\"submit\"></td>";
            echo "<td>&nbsp;</td>";
            echo "</tr>";

            echo "<tr>";
            echo "<td colspan='5' align='right'>--</td>";
            echo "<td align='right'><a href='shoppingcheckout.php'>Checkout</a></td>";
            echo "<td>&nbsp;</td>";
            echo "</tr>";            
        }
        else
        {
            echo "<tr><td>Your Shopping cart is currently empty</td><tr>";
        }
        echo "</table>";
        echo "</form>";
        function getsubcategoryname($subcategoryidf){
            $subcategoryresult = mysql_query("SELECT * FROM tblsubcategories WHERE subcategoryid = $subcategoryidf");
            $mysubcategory = mysql_fetch_array($subcategoryresult);
            $subcategoryname = $mysubcategory['subcategoryname'];
            return $subcategoryname;
        }

        ?>
</td>
<!--Right Block Ends -->

<!--Content Block Ends -->
</tr>

<tr>
<td colspan="2">	
	<div id="sub_block2">
        <?php include('incbott.php'); ?>
	</div>
</td>
</tr>
</table>
</center>
</body>
</html>

What happens when I try to run the script online is:
1) I successfully add the first itrm to the Cart and the shopping cart displays
2) When I add additional items, I get an error saying:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

The error appears above the Shopping cart
3) All the other items in the cart display except the first one
4) The Update and Checkout links do NOT display

What am I missing?

**PHPycho** · Nov 17, 2009 11:09

PHP Code:


 $subcategoryresult = mysql_query("SELECT * FROM tblsubcategories WHERE subcategoryid = $subcategoryidf");

What happens when $subcategoryidf is blank in above query?

**owentech** · Nov 18, 2009 07:53

I have not tried that, but I do not think that has arisen.
And even if it did, why would it do that only for the first item, regardless of what item that is?
But I will look into it.
Maybe the function is running without a value being passed.

**PHPycho** · Nov 19, 2009 01:48

Originally Posted by owentech

I have not tried that, but I do not think that has arisen.
And even if it did, why would it do that only for the first item, regardless of what item that is?
But I will look into it.
Maybe the function is running without a value being passed.

if $subcategoryidf is blank then there will be mysql error as the query will be invalid.
In such cases using values in quotes(suited for mysql only) may save you from such errors.

Thanks

**hash** · Nov 19, 2009 02:13

too hard to read that code (use the php tags, there is a button), but, echo all queries, copy paste and run them on the server (phpmyadmin or whatever).

If one of the queries does have an error, find out what it is, and then find out how it is generated in the code.

**owentech** · Nov 26, 2009 07:11

Hi
I replaced

PHP Code:


            foreach ($mycart as $itemqty) 

            {

                $cartitemid = key($mycart);

with

PHP Code:


foreach ($mycart as $cartitemid => $itemqty) 

            {

and it worked!
:-)

Thanks

User Tag List

Thread: Bug in Shopping Cart Array

Thread Tools

Display

Bug in Shopping Cart Array

Bookmarks

Bookmarks

Posting Permissions