Handling user input is a vital part of web development, as it allows you to create interactive web applications. In this lesson, we'll explore how to create and process HTML forms using PHP, including input validation and security best practices.

Creating an HTML Form

To create an HTML form, use the <form> element and various input elements, such as <input>, <textarea>, and <select>. You must specify a method (GET or POST) and an action (the URL of the PHP script that will process the form data).

<form method="POST" action="process_form.php">
  <label for="name">Name:</label>
  <input type="text" id="name" name="name">
  <br>
  <label for="email">Email:</label>
  <input type="email" id="email" name="email">
  <br>
  <input type="submit" value="Submit">
</form>

Processing Form Data

In your PHP script, you can access the submitted form data through the $_GET or $_POST superglobal arrays, depending on the form method you specified.

$name = $_POST["name"];
$email = $_POST["email"];

Input Validation

It's crucial to validate user input before processing it, as it helps prevent security vulnerabilities and ensures that the data is in the correct format.

1. Check if the input is not empty:

if (empty($name)) {
  echo "Name is required.";
}

1. Validate an email address:

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
  echo "Invalid email format.";
}

Security Best Practices

1. Use htmlspecialchars() to convert special characters to HTML entities, which prevents Cross-Site Scripting (XSS) attacks.

$name = htmlspecialchars($_POST["name"]);
$email = htmlspecialchars($_POST["email"]);

1. Use prepared statements to prevent SQL Injection attacks when working with databases.

$stmt = $db->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->bind_param("ss", $name, $email);
$stmt->execute();

Actionable Work:

Practice PHP forms and input handling by completing the following exercises: