Add-cart.php Num «99% Premium»

<?php
session_start();
// Initialize cart if not exists
if (!isset($_SESSION['cart'])) 
$_SESSION['cart'] = [];

// Get product ID and quantity from request
$product_id = isset($_GET['id']) ? (int)$_GET['id'] : 0;
$quantity = isset($_GET['num']) ? (int)$_GET['num'] : 1;
// Validate inputs
if ($product_id <= 0) 
header('Location: products.php?error=invalid_product');
exit;
 add-cart.php num
if ($quantity <= 0) 
$quantity = 1;

// Optional: Fetch product details from database to validate
// $product = getProductById($product_id);
// if (!$product) 
//     header('Location: products.php?error=product_not_found');
//     exit;
//  // Get product ID and quantity from request
// Add to cart logic
if (isset($_SESSION['cart'][$product_id])) 
// Product exists, update quantity
$_SESSION['cart'][$product_id] += $quantity;
 else 
// New product, add to cart
$_SESSION['cart'][$product_id] = $quantity;

// Optional: Set success message
$_SESSION['cart_message'] = "Product added to cart successfully!"; if ($quantity &lt;= 0) 
$quantity = 1;
// Redirect back to previous page or product page
$redirect = isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : 'products.php';
header("Location: $redirect");
exit;
?>

INSERT INTO cart (user_id, product_id, quantity) 
VALUES (?, ?, ?)
ON DUPLICATE KEY UPDATE quantity = quantity + VALUES(quantity);

Before writing code, it is essential to understand what add-cart.php actually needs to do. It is not simply "saving an item." The script must: