MongoDB Adapter

MongoDB Adapter

InitPHP\Sessions\Adapters\MongoDBAdapter stores each session as a single document in a MongoDB collection.

Requirements: ext-mongodb.

Each document looks like:

{ "_id": "<session id>", "data": "<payload>", "timestamp": 1716998400 }

timestamp (Unix time) is refreshed on every write and used by garbage collection.

Options

Option	Type	Default	Notes
dsn	string	—	Required. MongoDB connection string.
collection	string	—	Required. Namespace as database.collection.

The legacy option key collation is still accepted as an alias for collection, for backward compatibility with older configs.

Missing dsn/collection throws a SessionInvalidArgumentException; a failed connection throws a SessionAdapterException; a missing ext-mongodb throws a SessionNotSupportedAdapter.

Usage

use InitPHP\Sessions\Session;
use InitPHP\Sessions\Adapters\MongoDBAdapter;

$adapter = new MongoDBAdapter([
    'dsn'        => 'mongodb://127.0.0.1:27017',
    'collection' => 'app.sessions', // "database.collection"
]);

Session::createImmutable($adapter)->start();

Garbage collection

gc() deletes documents whose timestamp is older than gc_maxlifetime and returns the number removed. It runs on PHP's normal GC schedule, or manually:

$deleted = $adapter->gc(3600);

For automatic expiry without relying on PHP's GC, you can additionally create a MongoDB TTL index on a date field — but note this adapter stores timestamp as an integer, so a TTL index would require storing a UTCDateTime instead. The built-in gc() is the supported path.

Behaviour notes

• write() upserts by _id, so repeated writes to the same session update the existing document instead of inserting duplicates.
• read() returns the document's data, or '' for an unknown session.
• destroy() deletes the single matching document.

See also

• Adapters overview
• PDO Adapter — the SQL equivalent.