PHP - How to accomplish this if? - syntax

Question

I am creating an order cart.
On the page that displays the cart, it checks if a value stored in the session $order corresponds with an id of a row in a mysql table. If this match exists, then the corresponding row is returned.
Within this process, I am trying to retrieve the quantity value stored in the session $quantity that corresponds to the id of the row in the table.
Each value in $order and $quantityis assigned a name, which is the id of the item they were added from.
This is the code that adds the order to the cart:
if (isset($_POST['action']) and $_POST['action'] == 'Order')
{
// Add item to the end of the $_SESSION['order'] array
$_SESSION['order'][$_POST['id']] = $_POST['id'];
$_SESSION['quantity'][$_POST['id']] = $_POST['quantity'];
header('Location: .');
exit();
}
This is the code on the cart page:
foreach ($order as $item)
foreach ($quantity as $amount)
{
mysql_data_seek( $productsSql, 0); //<- this line, to reset the pointer for every EACH.
while($row = mysql_fetch_assoc($productsSql))
{
$itId = $row['id'];
$itDesc = $row['desc'];
$itPrice1 = $row['price1'];
if ($item == $itId)
{
$pageContent .= '
<tr>
<td>'.$itDesc.'</td>
<td>'.if ($item[''.$itId.''] == $amount[''.$itId.'']) {echo $amount}.'</td>
<td>R'.number_format($itPrice1*$amount, 2).'</td>
</tr>
';
}
}
}
This row is producing a syntax error:
<td>'.if ($item[''.$itId.''] == $amount[''.$itId.'']) {echo $amount}.'</td>
What is the problem here for starters?
Secondly, how would I need to do to accomplish the task that I am facing?
Any input on this would be greatly appreciated!

Answer 1

Could you try this?
<td>'.($item[$itId] == $amount[$itId] ? $amount : '').'</td>
This is a ternary operator, look at http://en.wikipedia.org/wiki/Ternary_operation

Answer 2

You can't simply add conditional statements like that while you're building a string.
You can do this, however
<td>' . ($item[$itId] == $amount[$itId]) ? $amount : null . '</td>
but you should use a more legible method.
Another issue you may get is if $amount is an array, you won't be able to print it as a string. If, however, $amount is an object with ArrayAccess interface, you can print it with the __toString() method; but that's another story.

Answer 3

The code for creating the cart page has several issues.
You walk over items and over quantities, which will probably give you duplicate outputs.
$item is a plain string, so I wonder what $item[$itId] is supposed to do?
You walk over your complete result set several times which actually is not necessary. I really hope that "$productSql" isn't a "select * from product", otherwhise this might get REAL slow in production mode.
I suggest creating a good SQL for getting the data and using this as a basis for filling the page:
// note this has SQL-injection issues, so you really need to make sure that $order contains no crap
$productsSql = mysql_query("select * from product where id in (".join($order, ',').")");
// you now have a result set with all products from your order.
while($row = mysql_fetch_assoc($productsSql))
{
$itId = $row['id'];
$itDesc = $row['desc'];
$itPrice1 = $row['price1'];
// session contains the quantity array mapping ID -> Quantity, so grab it from there
$itQuantity = $quantity[$itId];
// finally calculate the price
$itPrice = number_format($itPrice1*$itQuantity, 2);
// now you have all data for your template and can just insert it.
// if you use double quotes you can put the $xyz into the string directly
$pageContent .= "
<tr>
<td>$itDesc</td>
<td>$itQuanty</td>
<td>R $itPrice</td>
</tr>
";
}