Symfony can't detect the roles from FOSUser - symfony

Question

I am setting up the user management for a website with FOSUser for the first time and I'm having some trouble figuring out where I mess up.
The role is in the database, in the roles column, like this:
a:1:{i:0;s:10:"ROLE_ADMIN";}
When I do a var_dump($this->getUser()) from the controller, I get this:
(...)
["roles":protected]=> array(1) { [0]=> string(10) "ROLE_ADMIN" }
(...)
So everything's fine over here too.
When I try either if ($this->get('security.context')->isGranted('ROLE_ADMIN')) from the controller or {% if is_granted('ROLE_ADMIN') %} from a twig template, Symfony doesn't detect the role. The profiler also tells me there is only the ROLE_USER role.
Here is my app/config/security.yml file:
security:
providers:
main:
id: fos_user.user_provider.username
encoders:
Site\UserBundle\Entity\User: sha512
role_hierarchy:
ROLE_MODERATOR: [ROLE_USER]
ROLE_ADMIN: [ROLE_MODERATOR]
firewalls:
main:
pattern: ^/
anonymous: true
form_login:
login_path: fos_user_security_login
check_path: fos_user_security_check
logout:
path: fos_user_security_logout
target: /
remember_me:
key: %secret%
default:
anonymous: ~

Answer 1

It looks like you didn't clear the cache. Try to clear cache for your environment
php app/console cache:clear --env=prod #for prod env
or
php app/console cache:clear #for dev env

Answer 2

To help confused passers-by:
In case you have followed the Symfony security tutorial at http://symfony.com/doc/current/security/entity_provider.html#create-your-user-entity, you may have implemented a method like this:
public function getRoles()
{
return array('ROLE_USER');
}
If you have switched to FOSUserBundle later on, you may have forgotten to remove this method. For me, this was the (home-made) issue why my users' roles didn't load properly.

Answer 3

If i am not confuse then you have in your line in security.yml
role_hierarchy:
ROLE_MODERATOR: [ROLE_USER]
ROLE_ADMIN: [ROLE_MODERATOR]
which describe that in both roles you have entered the value
ROLE_USER
so you should do like following lines
role_hierarchy:
ROLE_MODERATOR: [ROLE_USER]
ROLE_ADMIN: [ROLE_ADMIN]
ROLE_SUPER_ADMIN: [ROLE_MODERATOR,ROLE_ADMIN]