Is it possible to unset private_tempstore values?

Question

I have a block that creates a private_tempstore value (which I understand works exactly like PHP sessions).

How do I unset that value.

This is the code I am using for the block.

class SsoSessionBlock extends BlockBase {
    /**
     * {@inheritdoc}
     */
    public function build(){
        $value = 'dav';
        $session = \Drupal::service('user.private_tempstore')->get('achva_sso');
        $session->set('name', $value);


        return [
            '#type' => 'markup',
            '#markup' => $this->t('The output of super SsoSessionBlock block.'),
        ];
    }
}

I saw this method, but I am not sure how I am supposed to use it.

I tried the following code, but I get an error.

namespace Drupal\achva_sso\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\Core\Routing\TrustedRedirectResponse;
use Drupal\user;


class SsoController extends ControllerBase{
    public function ssoLogout(){

        $session = \Drupal::service('user.private_tempstore')->get('achva_sso');
        PrivateTempStore::delete('name');

        if(isset($session)){
            $status = $session .' is logged in';
        }else{
            $status = 'is logged out';
        }
        return[
            '#type' => 'markup',
            '#markup' => '<p>' . $status . '</p>' ,
        ];



    }
}

How do I unset a value I previously set?

Answer 1

I have a block that creates a private_tempstore value (which I understand works exactly like PHP sessions).

No, both are for different use cases.

Private tempstore is used mainly for larger quantities of data. To store a single value it would be too much overhead. Instead use the session object of the current request:

$request = \Drupal::request(); 
// in a class inject RequestStack and $request = $this->requestStack->getCurrentRequest();
// or get the request as controller parameter, see link below
$session = $request->getSession();

// set a value
$session->set('my_value', $my_value);

// unset a value
$session->remove('my_value');

This is the official Drupal 8 way to store session data and since you've tagged the question with sessions this probably what you are looking for, see Access session data through the Request object

Answer 2

delete() is the method to delete a value in the store.

$session = \Drupal::service('user.private_tempstore')->get('achva_sso');
$session->delete('name');

'name' is the value passed as first argument in any call to set().

You don't use PrivateTempStore::delete() since it's not a static method and it would throw errors or warnings, if called as static method.

As side note, user.private_tempstore is a deprecated service. Instead, the tempstore.private service should be used. (See User module's user.private_tempstore and user.shared_tempstore services moved to core for more details.) In the latest Drupal 8.5.x version, the service is marked as deprecated directly in the user.services.yml file.

class: Drupal\user\PrivateTempStoreFactory
arguments:
  - '@keyvalue.expirable'
  - '@lock'
  - '@current_user'
  - '@request_stack'
  - '%tempstore.expire%'
deprecated: 'The "%service_id%" service is deprecated. You should use the ''tempstore.private'' service instead. See https://www.drupal.org/node/2935639.'
tags:
  - { name: backend_overridable }

It should also be better to use dependency injection: A class extending BlockBase, or ControllerBase, can implement the create() method to load new dependencies.