PHP native session handling with session_set_save_handler() allows you to store session data in MongoDB instead of the default PHP session files.

The normal PHP functions remain the same:

• session_start() — starts or resumes a session.
• $_SESSION[] — stores and retrieves session variables.
• session_set_save_handler() — registers a custom handler for storing sessions.

Important: The PHP function is named session_set_save_handler(), not http_session_save_handler().

1. Normal PHP session example

Create a file named normal_session.php.

<?php
session_start();

$_SESSION['username'] = 'Rahul';
$_SESSION['course'] = 'BCA';

echo "Username: " . $_SESSION['username'];
echo "<br>Course: " . $_SESSION['course'];
?>

Output:

Username: Rahul
Course: BCA

By default, PHP stores the session data in server-side session files.

2. PHP session handling using MongoDB

This example uses session_set_save_handler() to save session data in a MongoDB collection.

Step 1: Install the MongoDB library

Open Command Prompt in your project folder and run:

composer require mongodb/mongodb

Make sure the MongoDB PHP extension is enabled and your MongoDB server is running.

Step 2: Create mongodb_session.php

<?php
require_once __DIR__ . '/vendor/autoload.php';

use MongoDB\Client;

$client = new Client("mongodb://localhost:27017");
$collection = $client->stud->sessions;

class MongoSession implements SessionHandlerInterface
{
    private $collection;

    public function __construct($collection)
    {
        $this->collection = $collection;
    }

    public function open(string $path, string $name): bool
    {
        return true;
    }

    public function close(): bool
    {
        return true;
    }

    public function read(string $id): string|false
    {
        $doc = $this->collection->findOne(['_id' => $id]);

        return $doc ? $doc->data : '';
    }

    public function write(string $id, string $data): bool
    {
        $this->collection->updateOne(
            ['_id' => $id],
            ['$set' => [
                'data' => $data,
                'updated_at' => time()
            ]],
            ['upsert' => true]
        );

        return true;
    }

    public function destroy(string $id): bool
    {
        $this->collection->deleteOne(['_id' => $id]);

        return true;
    }

    public function gc(int $max_lifetime): int|false
    {
        $result = $this->collection->deleteMany([
            'updated_at' => [
                '$lt' => time() - $max_lifetime
            ]
        ]);

        return $result->getDeletedCount();
    }
}

$handler = new MongoSession($collection);

session_set_save_handler($handler, true);

session_start();

$_SESSION['username'] = 'Rahul';
$_SESSION['course'] = 'BCA';

echo "Username: " . $_SESSION['username'];
echo "<br>Course: " . $_SESSION['course'];
?>

This version uses PHP 8 or later.

Step 3: Run the program

Open the file through your local server, for example:

http://localhost/mongodb_session.php

Output:

Username: Rahul
Course: BCA

Step 4: Check the data in MongoDB

Open MongoDB Compass and execute:

use stud
db.sessions.find()

Example document:

{
    _id: "PHP-generated-session-id",
    data: "username|s:5:\"Rahul\";course|s:3:\"BCA\";",
    updated_at: 1792130000
}

The actual session ID and serialized data will be generated by PHP.

3. How session_set_save_handler() works

The important line is:

session_set_save_handler($handler, true);

It tells PHP to use your MongoDB handler for session storage instead of its default file-based handler.

Remember: Register the handler before calling session_start(). For production applications, also configure secure session cookies, handle database errors, and ensure expired records are cleaned up reliably.

Difference between default PHP sessions and MongoDB sessions

What is http session in PHP?

In PHP, http_session is not a standard built-in PHP session function. You may be referring to HTTP sessions in general or to session_set_save_handler().

1. What is an HTTP session?

HTTP is a stateless protocol. This means a web server does not automatically remember a user’s previous request.

An HTTP session allows a website to maintain user-specific information across multiple requests, such as:

• Username after login
• Shopping cart items
• User ID
• User preferences

PHP commonly manages this using sessions.

2. Simple PHP HTTP session example

Create a file named session.php.

<?php
session_start();

$_SESSION['username'] = 'Rahul';

echo "Welcome " . $_SESSION['username'];
?>

Output:

Welcome Rahul

Here, session_start() starts or resumes the PHP session, and $_SESSION stores the user’s session data.