Fetching array cart php - 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

Answer 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.

Answer 2

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.