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# The persistent data handler interface for the Facebook SDK for PHP
The persistent data handler interface stores values in a persistent data store. By default the SDK for PHP uses native PHP sessions to store the persistent data. You can overwrite this behavior by coding to the `Facebook\PersistentData\PersistentDataInterface`.
## Facebook\PersistentData\PersistentDataInterface {#overview}
If you're using a web framework that handles persistent data for you, you might want to code a custom persistent data handler to ensure that your persistent storage is being handled consistently.
For example if you are using Laravel, a custom handler might look like this:
~~~~
use Facebook\PersistentData\PersistentDataInterface;
class MyLaravelPersistentDataHandler implements PersistentDataInterface
{
/**
* @var string Prefix to use for session variables.
*/
protected $sessionPrefix = 'FBRLH_';
/**
* @inheritdoc
*/
public function get($key)
{
return \Session::get($this->sessionPrefix . $key);
}
/**
* @inheritdoc
*/
public function set($key, $value)
{
\Session::put($this->sessionPrefix . $key, $value);
}
}
~~~~
To enable your custom persistent data handler implementation in the SDK, you can set an instance of the handler to the `persistent_data_handler` config of the `Facebook\Facebook` super service.
~~~~
$fb = new Facebook\Facebook([
// . . .
'persistent_data_handler' => new MyLaravelPersistentDataHandler(),
// . . .
]);
~~~~
Alternatively, if you're working with the `Facebook\Helpers\FacebookRedirectLoginHelper` directly, you can inject your custom handler via the constructor.
~~~~
use Facebook\Helpers\FacebookRedirectLoginHelper;
$myPersistentDataHandler = new MyLaravelPersistentDataHandler();
$helper = new FacebookRedirectLoginHelper($fbApp, $myPersistentDataHandler);
~~~~
## Method Reference {#method-reference}
### get() {#get}
~~~~
public mixed get(string $key)
~~~~
Returns a value from the persistent data store or `null` if the value does not exist.
### set() {#set}
~~~~
public void set(string $key, mixed $value)
~~~~
Sets a value to the persistent data store.