[FIXED] CakePHP 3 "Login As" wtih Multiple Auth Sessions

Issue

Using prefixes, I have separate sessions and logins for admins versus users. For example the AppController.php has:

    if ($this->request->prefix == 'admin') {

        $this->loadComponent('Auth', [
            'authenticate' => [
                'Form' => [
                    'userModel' => 'Admins',
                    'fields' => ['username' => 'email', 'password' => 'password']
                ],
            ],
            'loginAction' => [
                'controller' => 'Admins',
                'action' => 'login'
            ],
            'loginRedirect' => [
                'controller' => 'Admins',
                'action' => 'index'
            ],
            'logoutRedirect' => [
                'controller' => 'Admins',
                'action' => 'login',
            ],
            'storage' => [
                'className' => 'Session',
                'key' => 'Auth.Admin',              
            ],
        ]);

    } else {

        $this->loadComponent('Auth', [
            'authenticate' => [
                'Form' => [
                    'userModel' => 'Users',
                    'fields' => ['username' => 'email', 'password' => 'password']
                ],
            ],
            'loginAction' => [
                'controller' => 'Users',
                'action' => 'login'
            ],
            'loginRedirect' => [
                'controller' => 'pages',
                'action' => 'home'
            ],
            'logoutRedirect' => [
                'controller' => 'Users',
                'action' => 'login',
            ],
            'storage' => [
                'className' => 'Session',
                'key' => 'Auth.User',               
            ],
        ]);

    }

This is working fine in that users who visit example.com/admin get redirected to the admin login area, users who visit example.com get redirect to the user login area, and users can be logged into one, the other, or both simultaneously without interfering with each other.

The problem comes when I want admins to be able to "login as" another user. In CakePHP2 I was able to do this:

    AuthComponent::$sessionKey = 'Auth.User'; // solution from http://stackoverflow.com/questions/10538159/cakephp-auth-component-with-two-models-session
    $this->Auth->loginAction = array('admin'=>false,'controller'=>'accounts','action'=>'login');
    $this->Auth->loginRedirect = array('admin'=>false,'controller'=>'pages','action'=>'home');
    $this->Auth->logoutRedirect = array('admin'=>false,'controller'=>'accounts','action'=>'login');
    $this->Auth->authenticate = array(
        'Custom' => array(
            'userModel' => 'Account',
            'fields' => array('username' => 'number'),
        )
    );
    if (!$this->Auth->login($account['Account'])) {
        throw new NotFoundException(__('Could not login to account'));
    }

    return $this->redirect(array('admin' => false, 'controller' => 'getting_started', 'action' => 'index'));

And everything worked fine. But in CakePHP3 the AuthComponent::$sessionKey property doesn't appear to be accessible, instead I think I'm meant to use $this->Auth->config. But when I use this code:

public function loginas($id = null)
{

    $user = $this->Users->get($id, [
        'contain' => []
    ]);

    $this->Auth->config([
        'authenticate' => [
            'Form' => [
                'userModel' => 'Users',
                'fields' => ['username' => 'email', 'password' => 'password']
            ],
        ],
        'loginAction' => [
            'controller' => 'Users',
            'action' => 'login'
        ],
        'loginRedirect' => [
            'controller' => 'pages',
            'action' => 'home'
        ],
        'logoutRedirect' => [
            'controller' => 'Users',
            'action' => 'login',
        ],
        'storage' => [
            'className' => 'Session',
            'key' => 'Auth.User',               
        ],
    ]);

    $this->Auth->setUser($user->toArray());
    return $this->redirect([
        'prefix' => false,
        'controller' => 'pages',
        'action' => 'home',
    ]);     
}

I can successfully "login as", however it ALSO overwrites the user information for the existing admin session with the normal user details.

How can I get CakePHP 3 to leave the Auth.Admin session completely alone, and set up a new Auth session against the Auth.User session key (which happens to open in a new tab)?

Solution

OK I think I have this figured out, I needed to use $this->Auth->__set('sessionKey', 'Auth.User'); before calling $this->Auth->config().

public function loginas($id = null)
{

    $user = $this->Users->get($id, [
        'contain' => []
    ]);

    $this->Auth->__set('sessionKey', 'Auth.User');

    $this->Auth->config([
        'authenticate' => [
            'Form' => [
                'userModel' => 'Users',
                'fields' => ['username' => 'email', 'password' => 'password']
            ],
        ],
        'loginAction' => [
            'controller' => 'Users',
            'action' => 'login'
        ],
        'loginRedirect' => [
            'controller' => 'Pages',
            'action' => 'home'
        ],
        'logoutRedirect' => [
            'controller' => 'Users',
            'action' => 'login',
        ],
        'storage' => [
            'className' => 'Session',
            'key' => 'Auth.User',               
        ],
    ]);

    $this->Auth->setUser($user->toArray());
    return $this->redirect([
        'prefix' => false,
        'controller' => 'Pages',
        'action' => 'home',
    ]);     

Answered By - sverreg