symfony entity catching up inversed Values in many to many -

i'm trying setup many many between fos userbundle , own group bundle can group users. working fine. can set new group , can add many users group to. when want check if user in group, index join column error. think didn't understand usage of manytomany correct way nice if can me getting point.

my entities like:

user:

    class user extends baseuser {   /** * @orm\column(type="integer") * @orm\id * @orm\generatedvalue(strategy="auto") */ protected $id;      /**      * @orm\column(type="string", length=255, nullable=true)      */     protected $usergroups; //....// 

and group entity looks like:

    /**      * @orm\manytomany(targetentity="pruserbundle\entity\user", inversedby="id")      * @orm\joincolumn(name="id", referencedcolumnname="id")      * @var user      */      private $user; //....     /**      * add user      *      * @param \pruserbundle\entity\user $user      * @return lieferanten      */     public function adduser(\pruserbundle\entity\user $user)     {         $this->user[] = $user;          return $this;     }      /**      * remove user      *      * @param \pruserbundle\entity\user $user      */     public function removeuser(\pruserbundle\entity\user $user)     {         $this->user->removeelement($user);     }      /**      * user      *      * @return \doctrine\common\collections\collection       */     public function getuser()     {         return $this->user;     } 

when try catch users in group, error:

$group=$em->getrepository('prgroupbundle:group')->findall(); var_dump($lfr[0]->getuser()->getid()); 

i guess missunderstood how handle bidirectional manytomany. or can use manytoone also?