1. Introduction
In this lesson, we delve deeper into an essential aspect of web development—working with forms and data in PHP 8. Mastering the art of handling form data efficiently and securely is a cornerstone for building interactive and dynamic web applications. Forms serve as the bridge between the user and the server, enabling the seamless flow of data. They are instrumental in gathering input from users, which could range from simple text inputs to file uploads.
The data collected via forms can serve various purposes, such as user registration, login authentication, data filtering, and much more. However, working with forms also poses certain security risks. A lack of proper validation and sanitization could leave your application vulnerable to malicious attacks. Therefore, understanding how to process form data securely is crucial.
In this lesson, we will start by understanding the basic HTTP methods involved in form submission, namely GET and POST. Following this, we will delve into creating simple forms, processing form data, validating and sanitizing user input to ensure it’s safe and adheres to the expected format, and finally, implementing measures to secure form submissions against Cross-Site Request Forgery (CSRF) attacks.
As you progress through this lesson, you’ll acquire the knowledge and skills necessary to create forms, process user inputs securely, and build more interactive and user-friendly web applications. Before diving into the lesson, if you need a refresher on any of the previous topics, feel free to navigate through the PHP 8 Free Course index.
Whether you are developing a simple contact form, a complex multi-step registration form, or anything in between, the principles covered in this lesson will provide a solid foundation to ensure your forms and data in PHP 8 are both functional and secure.
PHP 8 Free Course – Lesson 8
2. Understanding HTTP Methods
Forms can be submitted using two primary HTTP methods: GET and POST.
- GET: Suitable for fetching data; form data is appended to the URL.
- POST: Suitable for submitting sensitive or large amounts of data; form data is included in the body of the request.
3. Creating Forms
Creating a form in HTML that submits data to a PHP script is straightforward.
// forms and data in PHP 8
// creating forms
<form action="process.php" method="post">
Name: <input type="text" name="name"><br>
Email: <input type="text" name="email"><br>
<input type="submit" value="Submit">
</form>4. Processing Forms and Data in PHP 8
Once the form is submitted, the data can be accessed in PHP using the $_POST or $_GET superglobals, depending on the method used.
$name = $_POST['name'];
$email = $_POST['email'];5. Validating Form Data
Validation ensures the data submitted is correct and safe to be used. Here are some validation examples:
// forms and data in PHP 8
// Validation
if (empty($_POST["name"])) {
$nameErr = "Name is required";
} else {
$name = test_input($_POST["name"]);
}
if (filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
$email = $_POST['email'];
} else {
$emailErr = "Invalid email format";
}
// Additional validation examples are provided later in this lesson.6. Sanitizing Forms and Data in PHP 8
Sanitizing ensures the data is clean and free from any malicious code.
$name = filter_input(INPUT_POST, 'name', FILTER_SANITIZE_STRING);
$email = filter_input(INPUT_POST, 'email', FILTER_SANITIZE_EMAIL);7. Cross-Site Request Forgery (CSRF) Protection
CSRF attacks primarily target state-changing requests, not data theft, as attackers trick the user into submitting a request to a web app on which they’re authenticated. To mitigate this, it’s essential to implement anti-CSRF tokens in your forms. Here’s a more detailed approach to implementing CSRF protection in PHP:
1. Generating CSRF Tokens:
- Random Token Generation: Generate a random token each time the form is created. Store this token in the user’s session and also include it within the form as a hidden field.
session_start();
$token = bin2hex(random_bytes(32));
$_SESSION['token'] = $token;
