Passing Information Between Pages in PHP
When developing dynamic web applications, it is common to pass information from one page to another. PHP provides multiple ways to transfer data between pages, including GET, POST, sessions, cookies, and hidden form fields. Each method has specific use cases depending on security, performance, and usability requirements.
1. Methods for Passing Information Between Pages
| Method | Description | Use Case |
| GET Method | Sends data via the URL | Passing non-sensitive data like search queries |
| POST Method | Sends data in the request body | Securely submitting form data |
| Session Variables | Stores data across multiple pages | User authentication, shopping carts |
| Cookies | Stores small data on the client-side | User preferences, login details |
| Hidden Form Fields | Stores data in an HTML form but hides it from the user | Keeping track of user choices |
2. Passing Information Using the GET Method
How GET Works
- Data is appended to the URL in key-value pairs.
- Example: page2.php?name=John&age=25
- Maximum URL length: ~2000 characters.
- Data is visible in the browser’s address bar.
Example: Sending Data Using GET
Page 1: form.html
<!DOCTYPE html>
<html>
<head>
<title>GET Method Example</title>
</head>
<body>
<form action=”page2.php” method=”GET”>
Name: <input type=”text” name=”name”>
Age: <input type=”text” name=”age”>
<input type=”submit” value=”Submit”>
</form>
</body>
</html>
Page 2: page2.php
<?php
if(isset($_GET[‘name’]) && isset($_GET[‘age’])) {
$name = htmlspecialchars($_GET[‘name’]);
$age = htmlspecialchars($_GET[‘age’]);
echo “Hello, $name. You are $age years old.”;
} else {
echo “No data received.”;
}
?>
When to Use GET
Use GET when sending non-sensitive data. Suitable for search queries, filtering, pagination.
Do not use GET for passwords or personal data.
3. Passing Information Using the POST Method
How POST Works
- Data is sent in the request body (not visible in the URL).
- No character limit.
- More secure than GET.
Example: Sending Data Using POST
Page 1: form.html
<!DOCTYPE html>
<html>
<head>
<title>POST Method Example</title>
</head>
<body>
<form action=”page2.php” method=”POST”>
Name: <input type=”text” name=”name”>
Age: <input type=”text” name=”age”>
<input type=”submit” value=”Submit”>
</form>
</body>
</html>
Page 2: page2.php
<?php
if(isset($_POST[‘name’]) && isset($_POST[‘age’])) {
$name = htmlspecialchars($_POST[‘name’]);
$age = htmlspecialchars($_POST[‘age’]);
echo “Hello, $name. You are $age years old.”;
} else {
echo “No data received.”;
}
?>
When to Use POST
Use POST when sending sensitive or large data (e.g., passwords, file uploads). Suitable for form submissions, login systems. Not bookmarkable or cacheable like GET requests.
4. Passing Information Using Session Variables
How Sessions Work
- A session stores user data across multiple pages.
- Session data is stored on the server.
- A unique session ID is assigned to each user.
Example: Using PHP Sessions
Page 1: session_start.php (Set Session)
<?php
session_start();
$_SESSION[‘username’] = “JohnDoe”;
$_SESSION[‘user_role’] = “Admin”;
echo “Session variables are set.”;
?>
Page 2: session_display.php (Retrieve Session Data)
<?php
session_start();
if(isset($_SESSION[‘username’]) && isset($_SESSION[‘user_role’])) {
echo “Welcome, ” . $_SESSION[‘username’] . “. Your role is ” . $_SESSION[‘user_role’] . “.”;
} else {
echo “No session data found.”;
}
?>
Destroying a Session (logout.php)
<?php
session_start();
session_unset();
session_destroy();
echo “Session destroyed.”;
?>
When to Use Sessions
Ideal for user authentication, shopping carts, and dashboards. More secure than GET and POST. Data expires after a timeout or when the session is closed.
5. Passing Information Using Cookies
How Cookies Work
- A cookie is stored on the client’s browser.
- Can persist across browser sessions (e.g., “Remember Me” logins).
- Set using setcookie() in PHP.
Example: Using Cookies
Set a Cookie (set_cookie.php)
<?php
setcookie(“username”, “JohnDoe”, time() + (86400 * 7), “/”); // 7-day expiry
echo “Cookie has been set!”;
?>
Retrieve a Cookie (get_cookie.php)
<?php
if(isset($_COOKIE[‘username’])) {
echo “Welcome back, ” . $_COOKIE[‘username’];
} else {
echo “No cookie found.”;
}
?>
Delete a Cookie (delete_cookie.php)
<?php
setcookie(“username”, “”, time() – 3600, “/”); // Expire in the past
echo “Cookie has been deleted.”;
?>
When to Use Cookies
Good for storing user preferences, login details, tracking users. Data persists even after the browser is closed. Not secure (can be modified by the user). Limited storage (~4KB per cookie).
6. Passing Information Using Hidden Form Fields
How Hidden Fields Work
- Hidden fields store data inside a form but do not appear to the user.
- Used to persist values between form submissions.
Example: Using Hidden Fields
Page 1: form.html
<!DOCTYPE html>
<html>
<head>
<title>Hidden Fields Example</title>
</head>
<body>
<form action=”page2.php” method=”POST”>
<input type=”hidden” name=”userid” value=”12345″>
Name: <input type=”text” name=”name”>
<input type=”submit” value=”Submit”>
</form>
</body>
</html>
Page 2: page2.php
<?php
if(isset($_POST[‘name’]) && isset($_POST[‘userid’])) {
echo “User ID: ” . $_POST[‘userid’] . ” | Name: ” . $_POST[‘name’];
}
?>
When to Use Hidden Fields
Used when session or cookie storage is not available. Less secure than sessions (values are visible in the page source).
7. Conclusion
Each method of passing information between pages in PHP has its use cases:
| Method | Best Used For | Security |
| GET | Passing non-sensitive data in URLs | Low |
| POST | Secure form submissions | Medium |
| Sessions | Authentication, user state | High |
| Cookies | Storing user preferences | Medium |
| Hidden Fields | Persisting data in forms | Low |
For secure applications, sessions are the best choice, while GET and POST are great for form submissions. Cookies are useful for long-term storage but should not store sensitive data.