symfony - How to list entity in form -

i have entity hall can either welcome hall(subhall), or stand.

i'm stuck hall form (or @ least it's think needs edited). can't figure out how have display <select> of hall parent=0 need default option blank 0 value

here files:

hall entity:

<?php  namespace salonbundle\entity; use doctrine\orm\mapping orm;  /**  * hall  *  * @orm\table(name="hall")  * @orm\entity(repositoryclass="salonbundle\repository\hallrepository")  */ class hall {  /**  * @var int  *  * @orm\column(name="id", type="integer")  * @orm\id  * @orm\generatedvalue(strategy="auto")  */  private $idhall;   /**  * @var string  * @orm\column(name="name", type="string", length=255)  */  private $name;      /**      * @var integer      * @orm\column(name="parent", type="integer", options={"default":0})      */     private $parent;      /**      * @var      * @orm\onetomany(targetentity="salonbundle\entity\stand", mappedby="hall")      */     private $stand;   public function __construct()  {  $this->stand = new \doctrine\common\collections\arraycollection();  }   /**  * idhall  * @return integer  */  public function getidhall()  {  return $this->idhall;  }   /**  * set name  * @param string $name  * @return hall  */  public function setname($name)  {  $this->name = $name;   return $this;  }   /**  * name  * @return string  */  public function getname()  {  return $this->name;  }      /**      * set parent      * @param integer $parent      * @return hall      */     public function setparent($parent)     {         $this->parent = $parent;          return $this;     }      /**      * parent      * @return string      */     public function getparent()     {         return $this->parent;     }   /**  * add stand  * @param \salonbundle\entity\stand $stand  * @return hall  */  public function addstand(\salonbundle\entity\stand $stand)  {  $this->stand[] = $stand;   return $this;  }   /**  * remove stand  * @param \salonbundle\entity\stand $stand  */  public function removestand(\salonbundle\entity\stand $stand)  {  $this->stand->removeelement($stand);  }   /**  * stand  * @return \doctrine\common\collections\collection  */  public function getstand()  {  return $this->stand;  }      /**      * tostring      * @return string      */     public function __tostring() {         return $this->getname();     } } 

hall form :

<?php  namespace salonbundle\form;  use salonbundle\entity\hall; use symfony\component\form\abstracttype; use symfony\component\form\formbuilderinterface; use symfony\component\optionsresolver\optionsresolver;  class halltype extends abstracttype {  /**  * @param formbuilderinterface $builder  * @param array $options  */  public function buildform(formbuilderinterface $builder, array $options)  {  $builder  ->add('name')  ->add('parent') // need complete part  ;  }   /**  * @param optionsresolver $resolver  */  public function configureoptions(optionsresolver $resolver)  {  $resolver->setdefaults(array(  'data_class' => 'salonbundle\entity\hall'  ));  } } 

how should proceed ?

with 'query_builder' option can filter entities:

http://symfony.com/doc/current/reference/forms/types/entity.html#ref-form-entity-query-builder

$builder->add('users', entitytype::class, array(   'class' => 'appbundle:user',   'query_builder' => function (entityrepository $er) {       return $er->createquerybuilder('u')         ->orderby('u.username', 'asc');   },   'choice_label' => 'username', ));