User Impersonation

After deploying your application, you may occasionally need to 'impersonate' another user in order to debug problems that your customers report or to see the application in the state that your customers are seeing it.

Enabling Impersonation

To impersonate another user you can use the impersonate() method on the AuthenticationComponent. To impersonate a user you first need to load that user from your application's database:

// In a controller
public function impersonate(): \Cake\Http\Response
{
    $this->request->allowMethod(['POST']);

    $currentUser = $this->request->getAttribute('identity');

    // You should always check that the current user is allowed
    // to impersonate other users first.
    if (!$currentUser->isStaff()) {
        throw new NotFoundException();
    }

    // Fetch the user we want to impersonate.
    $targetUser = $this->fetchTable('Users')
        ->findById($this->request->getData('user_id'))
        ->firstOrFail();

    // Enable impersonation.
    $this->Authentication->impersonate($targetUser);

    return $this->redirect($this->referer());
}

Once you have started to impersonate a user, all subsequent requests will have $targetUser as the active identity.

Ending Impersonation

Once you are done impersonating a user, you can then end impersonation and revert back to your previous identity using AuthenticationComponent:

// In a controller
public function revertIdentity(): \Cake\Http\Response
{
    $this->request->allowMethod(['POST']);

    // Make sure we are still impersonating a user.
    if (!$this->Authentication->isImpersonating()) {
        throw new NotFoundException();
    }
    $this->Authentication->stopImpersonating();

    return $this->redirect($this->referer());
}

Limitations to Impersonation

There are a few limitations to impersonation.

1. Your application must be using the Session authenticator.
2. You cannot impersonate another user while impersonation is active. Instead you must stopImpersonating() and then start it again.