Fetching array cart php

Question

I have a following question. I store a shopping cart in an array session like below

session_start();
$id= $_GET['id'];
if(isset($_SESSION['cart']))
{
array_push($_SESSION['cart'], $id);
}
else
    $_SESSION['cart']= array($id);

header("location:cart.php");

And when I try to retrieve the cart. I get the same product id as many as I put to the cart.

<?php
if(!isset($_SESSION['cart'])) {
    echo "Your cart is empty.<br /><br /><a href='products.php'>Show products</a>";
} else {
    echo '<table border="0.2">';

    $total_price = 0;

    foreach($_SESSION['cart'] as $id) {
        $the_query = "select * from products where id='$id' GROUP BY id";

        $result = mysql_query($the_query) or die('Query failed: ' . mysql_error());

        $the_product = mysql_fetch_array($result, MYSQL_ASSOC);

        $total_price = $total_price + $the_product['price'];

        $href = "show_products.php?id=".$the_product['id'];
        //echo "<tr>";
        echo "<tr><td><a href='$href'>";
        echo "<img src='".$the_product['image_url_small']."' /></a></td>";
        echo "<td><strong>".$the_product['name']."</strong></td><td><em>$".$the_product['price']."</em>";
        echo "</td>";
        echo "<td> <a href='do_deletecart.php?id=". $the_product['id'] ."'>Delete item </a></td></tr>";
    }
    echo "<tr><td colspan='2'></td></tr>";
    echo "<tr><td style='text-align:center;font-size:40px;'>$</td><td><strong>Total</strong><br /><em>$".$total_price."</em></td></tr>";
    echo "</table>";
    echo "<br /><a href='empty_cart.php'>Empty Cart</a> <a href='showallproducts.php'>Show phones</a><br /><br />";
}

how can I make it show only one product id or name. Thank in advance

This code is highly vulnerable to SQL Injection. Please, sanitize your inputs and use a recent API — Touki
– Touki, Commented Apr 29, 2013 at 10:20

Subash · Accepted Answer · 2013-04-29 12:39:09Z

1

If I understand your question correctly, you are getting many results for the same product id. This is because you are storing same id values many time in the $_SESSION variable.

You could do the following to not repeat the same ids in the $_SESSION variable.

EDIT

For sake of completeness I have updated the code. Hope that helps.

index.php

<?php

session_start();

$id= isset($_GET['id']) ? $_GET['id'] : null;

if(!is_null($id)){
    if(isset($_SESSION['cart']) && count($_SESSION['cart']) > 0){

        // increment product quantity if already exists
        // or create a new one
        add_or_increment_product_to_cart($id, $_SESSION['cart']);

    } else {
        // initialize cart
        // add the first product
        $_SESSION['cart'] = array();
        array_push($_SESSION['cart'], (object) array('id' => $id, 'quantity' => 1));
    }
}

function add_or_increment_product_to_cart($id, $cart){

    foreach ($cart as $key => $product) {
        if($id == $product->id){
            $product->quantity++;
            return;
        }
    }

    array_push($_SESSION['cart'], (object) array('id' => $id, 'quantity' => 1));
}

header("location:cart.php");

Cart.php

<?php

session_start();

$cart = isset($_SESSION['cart']) ? $_SESSION['cart'] : null;

if($cart) {
    foreach ($cart as $key => $product) {
        $the_query = "SELECT * FROM products WHERE id=" . $product->id . " LIMIT 1";

        // your code to fetch the products from the database
        // what you have done is fine but vulnerable
        // PDO recommended 
    }
} else {
    echo "Your cart is empty.<br /><br /><a href='products.php'>Show products</a>";
}

Also please note that mysql_connect is deprecated and PDO class is the recommended and safe way to connect to the database. Your code is vulnerable to SQL Injection like @Touki said in his comment.

edited Apr 29, 2013 at 12:39

answered Apr 29, 2013 at 10:54

Subash

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3 Comments

Menno Over a year ago

Using an array() would work but is still a bit messy. I'd suggest instead of fixing symptoms, to fix the root of the problem (multiple instances of the same product ids).

Subash Over a year ago

Yes. I agree. The in_array() check makes sure that there is no repeated instances of the same id.

Menno Over a year ago

My mistake, I didn't read your example correct. This sample is used to inject any new ids instead of looping to print them.

Pudge601 · Accepted Answer · 2013-04-29 10:40:09Z

I would recommend performing only one query to retrieve all of the products, and then iterate the result of the query to populate the HTML. For example;

$the_query = "select * from products where id in (". implode(',', $_SESSION['cart']) .")";
$result = mysql_query($the_query);
while (($the_product = mysql_fetch_array($result, MYSQL_ASSOC))) {
    ...
}

This has the added bonus that you only perform one query, and would also only select one row per product.

It's worth noting, however, that the mysql_* methods are deprecated, and it would be advisable to start using another library such as mysqli or PDO.

On a related note, this code currently is very liable to SQL injection, and the input should ideally be sanitised before being put into a query string.

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