How to add shopping cart in php without logging in

In modern e-commerce, the shopping cart is an important interactive tool that can help customers select and purchase goods more conveniently. Generally speaking, customers need to log in before adding items to their shopping cart, but in some cases, we may need to provide a function that allows them to add items to their shopping cart without logging in. This article explains how to implement this functionality using PHP.

Use Cookies to Store Shopping Cart Data

If customers can add items to their shopping cart without logging in, then we need to use a way to distinguish different customers and their shopping cart data. A common way is to use cookies to store shopping cart data. A cookie is a small piece of data stored on the client that can be passed between the client and the server. By storing shopping cart data in cookies, we can restore the data the next time a customer visits our website, thus ensuring the consistency of the shopping cart data.

In order to achieve this function, we can create an add_to_cart.php file. When the customer clicks the "Add to Cart" button, the file will store the product information in the cookie in the background. The specific method is as follows:

1. In the add_to_cart.php file, first obtain the product ID and quantity to be added to the shopping cart through the GET or POST method.
2. Then, get the current shopping cart data through PHP’s $_SESSION variable. Under certain circumstances, the $_SESSION variable may become invalid, so some detection and handling of this is required.
3. Create an array to store shopping cart data (for example: $cart = array()).
4. If the shopping cart data already exists in $_SESSION, copy it to the $cart array.
5. Check whether the current item is already in the shopping cart. If yes, increase the quantity of that item in the cart; if not, add the new item to the cart.
6. Store the shopping cart data in a cookie so that it can be used the next time the user's shopping cart data is retrieved.
7. Save data such as the total quantity and price of the shopping cart to $_SESSION for subsequent use.

Code example:

<?php
session_start();
$product_id = $_GET[&#39;product_id&#39;];
$quantity = $_GET[&#39;quantity&#39;];

$cart = array();
if (isset($_SESSION[&#39;cart&#39;])) {
    $cart = $_SESSION[&#39;cart&#39;];
}

if (isset($cart[$product_id])) {
    $cart[$product_id][&#39;quantity&#39;] += $quantity;
} else {
    $cart[$product_id] = array(
        &#39;id&#39; => $product_id,
        'quantity' => $quantity,
        'price' => $price // 商品单价等其他信息可以根据需求添加
    );
}

$_SESSION['cart'] = $cart;
$total_items = count($cart);
$total_price = 0;
foreach ($cart as $item) {
    $total_price += $item['quantity'] * $item['price'];
}
$_SESSION['total_items'] = $total_items;
$_SESSION['total_price'] = $total_price;

setcookie('cart', serialize($cart), time() + 3600 * 24 * 30, '/');
header('Location: cart.php');
?>

Use JavaScript to implement shopping cart UI

In the above code, we use PHP to operate the shopping cart data and store the data In Cookies and $_SESSION. But we also need to present this data to users in a visual form. To do this, we can use JavaScript to create the user interface of the shopping cart.

Specifically, we can create a DOM node in the shopping cart page to display the quantity, total price and other information of the current shopping cart. The shopping cart data is then retrieved from the cookie or server via JavaScript code and presented to the user. In the shopping cart page, we can also provide some functions, such as increasing or decreasing the number of items in the shopping cart, deleting an item, and updating the shopping cart data in Cookie and $_SESSION.

Code example:

function update_cart() {
    var cart = {};
    if (getCookie('cart') != "") {
        cart = JSON.parse(getCookie('cart'));
    }
    var total_items = 0;
    var total_price = 0;
    for (var id in cart) {
        total_items += cart[id]['quantity'];
        total_price += cart[id]['quantity'] * cart[id]['price'];
    }
    document.getElementById('cart-total-items').innerHTML = total_items;
    document.getElementById('cart-total-price').innerHTML = total_price;
}

In the above code, we get the shopping cart data from Cookie through the getCookie() function. Then, use a for loop to iterate over the cart object and calculate the total quantity and total price of all items in the shopping cart. Finally, update this information into the HTML page.

Summary

This article briefly introduces how to use PHP and JavaScript to implement the function of adding products to the shopping cart without logging in. This functionality is achieved by storing the shopping cart data in a cookie, while using JavaScript to create the shopping cart UI and handle user interaction. The implementation of this function requires a certain degree of mastery of both PHP and JavaScript, and you also need to pay attention to some security issues, such as XSS and CSRF injection.

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