<?php

class MyUserStorage {
...

    public function setIdentity(IIdentity $identity = NULL) {
        // ukladma pouze id
        $this->getSessionSection(TRUE)->identityId = $identity ? $identity->getId() : null;
        return $this;
    }


    public function getIdentity() {
        if(!$session = $this->getSessionSection(FALSE)) return NULL;
        if(!$id = $session->identityId) return NULL;

        // nactu z doctrine
        return $this->em->getRepository(IdentityEntity::getClassName())->find($id);
    }