php - JMS serializer can't serialize: cannot access private property -

i'm trying serialize doctrine2 entity json using jms serializer bundle. have set up, when try serialize json following error:

fatal error: cannot access private property snow\frontbundle\entity\district::$id in e:\school\socialgeo augustus\coding\socialgeo-php\vendor\jms\metadata\src\metadata\propertymetadata.php on line 46

this controller code:

public function indexaction() {   $em = $this->getdoctrine()->getmanager();    $districts = $em->getrepository('snowfrontbundle:district')->findall();    $serializer = $this->get('jms_serializer');   echo $serializer->serialize($districts, 'json');    return array(     'districts' => $districts   ); } 

and lastly, district entity:

<?php  namespace snow\frontbundle\entity;  use doctrine\orm\mapping orm;  /**  * district  *  * @orm\table(name="district")  * @orm\entity(repositoryclass="snow\frontbundle\entity\repositories\districtrepository")  */ class district {   /**    * @var integer    *    * @orm\column(name="id", type="integer")    * @orm\id    * @orm\generatedvalue(strategy="auto")    */   public $id;    /**    * @var string    *    * @orm\column(name="name", type="string", length=100)    */   public $name;    /**    * @var string    *    * @orm\column(name="bigimage", type="string", length=100)    */   public $bigimage;    /**    * @var string    *    * @orm\column(name="smallimage", type="string", length=100)    */   public $smallimage;    /**    * @var string    *    * @orm\column(name="info", type="text")    */   public $info;    /**    *    * @orm\manytoone(targetentity="city", inversedby="districts")    * @orm\joincolumn(name="city_id", referencedcolumnname="id")    */   protected $city;    /**    *    * @orm\onetomany(targetentity="district", mappedby="city")    */   protected $locations;    /**    *    * @var \doctrine\common\collections\arraycollection $articles    * @orm\manytomany(targetentity="article", mappedby="districts")    */   protected $articles;    /**    *    * @var \doctrine\common\collections\arraycollection $workers    *    * @orm\manytomany(targetentity="user", inversedby="districts")    * @orm\jointable(name="workers_districts",    *     joincolumns={@orm\joincolumn(name="district_id", referencedcolumnname="id")},    *     inversejoincolumns={@orm\joincolumn(name="user_id", referencedcolumnname="id")}    * )    */   protected $workers;    /**    *    * @var \doctrine\common\collections\arraycollection $userbookmarks    * @orm\manytomany(targetentity="user", mappedby="favdistricts")    */   protected $userbookmarks;     /**    * id    *    * @return integer    */   public function getid() {     return $this->id;   }    /**    * set name    *    * @param string $name    * @return district    */   public function setname($name) {     $this->name = $name;      return $this;   }    /**    * name    *    * @return string    */   public function getname() {     return $this->name;   }    /**    * set info    *    * @param string $info    * @return district    */   public function setinfo($info) {     $this->info = $info;      return $this;   }    /**    * info    *    * @return string    */   public function getinfo() {     return $this->info;   }    /**    * set city    *    * @param \snow\frontbundle\entity\city $city    * @return district    */   public function setcity(\snow\frontbundle\entity\city $city = null) {     $this->city = $city;      return $this;   }    /**    * city    *    * @return \snow\frontbundle\entity\city    */   public function getcity() {     return $this->city;   }    /**    * constructor    */   public function __construct() {     $this->locations = new \doctrine\common\collections\arraycollection();   }    /**    * add locations    *    * @param \snow\frontbundle\entity\district $locations    * @return district    */   public function addlocation(\snow\frontbundle\entity\district $locations) {     $this->locations[] = $locations;      return $this;   }    /**    * remove locations    *    * @param \snow\frontbundle\entity\district $locations    */   public function removelocation(\snow\frontbundle\entity\district $locations) {     $this->locations->removeelement($locations);   }    /**    * locations    *    * @return \doctrine\common\collections\collection    */   public function getlocations() {     return $this->locations;   }    /**    * add articles    *    * @param \snow\frontbundle\entity\article $articles    * @return district    */   public function addarticle(\snow\frontbundle\entity\article $articles) {     $this->articles[] = $articles;      return $this;   }    /**    * remove articles    *    * @param \snow\frontbundle\entity\article $articles    */   public function removearticle(\snow\frontbundle\entity\article $articles) {     $this->articles->removeelement($articles);   }    /**    * articles    *    * @return \doctrine\common\collections\collection    */   public function getarticles() {     return $this->articles;   }    /**    *    * @return string    */   public function __tostring() {     return $this->getname();   }    /**    * add workers    *    * @param \snow\frontbundle\entity\user $workers    * @return district    */   public function addworker(\snow\frontbundle\entity\user $workers) {     $this->workers[] = $workers;      return $this;   }    /**    * remove workers    *    * @param \snow\frontbundle\entity\user $workers    */   public function removeworker(\snow\frontbundle\entity\user $workers) {     $this->workers->removeelement($workers);   }    /**    * workers    *    * @return \doctrine\common\collections\collection    */   public function getworkers() {     return $this->workers;   }    /**    * set bigimage    *    * @param string $bigimage    * @return district    */   public function setbigimage($bigimage) {     $this->bigimage = $bigimage;      return $this;   }    /**    * bigimage    *    * @return string    */   public function getbigimage() {     return $this->bigimage;   }    /**    * set smallimage    *    * @param string $smallimage    * @return district    */   public function setsmallimage($smallimage) {     $this->smallimage = $smallimage;      return $this;   }    /**    * smallimage    *    * @return string    */   public function getsmallimage() {     return $this->smallimage;   }     /**    * add userbookmarks    *    * @param \snow\frontbundle\entity\user $userbookmarks    * @return district    */   public function adduserbookmark(\snow\frontbundle\entity\user $userbookmarks) {     $this->userbookmarks[] = $userbookmarks;      return $this;   }    /**    * remove userbookmarks    *    * @param \snow\frontbundle\entity\user $userbookmarks    */   public function removeuserbookmark(\snow\frontbundle\entity\user $userbookmarks) {     $this->userbookmarks->removeelement($userbookmarks);   }    /**    * userbookmarks    *    * @return \doctrine\common\collections\collection    */   public function getuserbookmarks() {     return $this->userbookmarks;   } } 

does know why happening? seems can bit further if set public in entity, tells me i'm not supposed that. if so, symfony2 error saying:

an exception occurred while executing 'select t0.id id1, t0.title title2, t0.path path3, t0.description description4, t0.createddate createddate5, t0.publisheddate publisheddate6, t0.deleteddate deleteddate7, t0.published published8, t0.url url9, t0.location_id location_id10, t0.user_id user_id11, t0.mediatype_id mediatype_id12 media t0 t0.user_id = ?' params {"1":6}:  sqlstate[42s22]: column not found: 1054 unknown column 't0.location_id' in 'field list' 

thanks in advance can provide!

check here

http://jmsyst.com/libs/serializer/master/reference/annotations#accesstype

you can specify access type, in case should keep variables private/protected , add /** @accessor(getter="getid") */ annotation tell jms how id.

also, noted @forgottenbas, may need add @type("integer") annotation well.