Chapter 10: Web Development with PHP
In this chapter, we will explore web development with PHP. We will cover working with HTTP requests, handling form data, working with cookies and sessions, and implementing basic security measures.
10.1 Working with HTTP requests:
PHP provides superglobal variables like $_GET and $_POST to access data sent via HTTP GET and POST methods.
These variables allow us to retrieve user input from form submissions or query parameters.
Example:
php
""
<?php
// Handling HTTP GET request
$name = $_GET['name'];
echo "Hello, " . $name;
// Handling HTTP POST request
$username = $_POST['username'];
$password = $_POST['password'];
// Code to process the form data
?>
10.2 Handling form data:
HTML forms are a common way to collect user input on web pages.
PHP can process form data using the $_POST or $_GET superglobal variables.
We can validate and sanitize form data to ensure security and integrity.
Example:
php
""
<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
$name = $_POST['name'];
$email = $_POST['email'];
// Validate and process the form data
}
?>
10.3 Working with cookies and sessions:
Cookies and sessions allow us to store and retrieve user data across multiple page visits or requests.
Cookies are stored on the user's browser, while sessions are stored on the server.
PHP provides functions like setcookie(), $_COOKIE, session_start(), and $_SESSION for working with cookies and sessions.
Example:
php
""
<?php
// Setting a cookie
setcookie('username', 'John', time() + (86400 * 30), '/');
// Accessing a cookie
$username = $_COOKIE['username'];
// Starting a session
session_start();
// Storing data in a session
$_SESSION['user_id'] = 12345;
// Accessing session data
$userId = $_SESSION['user_id'];
?>
10.4 Basic security measures:
Web applications should implement basic security measures to protect against common vulnerabilities.
Measures include input validation, output encoding, password hashing, and protection against SQL injection and cross-site scripting (XSS) attacks.
Example:
php
""
<?php
// Validating user input
$email = $_POST['email'];
if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
// Valid email address
}
// Output encoding
$name = "<script>alert('XSS');</script>";
echo htmlspecialchars($name);
// Password hashing
$password = $_POST['password'];
$hashedPassword = password_hash($password, PASSWORD_DEFAULT);
// Protection against SQL injection
$username = $_POST['username'];
$query = "SELECT * FROM users WHERE username = '" . mysqli_real_escape_string($connection, $username) . "'";
?>
By following the explanations and examples in this chapter, you will gain a solid understanding of web development with PHP, allowing you to handle HTTP requests, process form data, work with cookies and sessions, and implement basic security measures to build robust and secure web applications.
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