Form submit error data_class formview - php

Question

I have a form builded by formbuilder
public function buildForm(FormBuilderInterface $builder, array $options){
$query = $this->em->createQueryBuilder();
$query->select('sn.serial_nr')
->from('KopictAdminBundle:SerialNumber', 'sn');
$serialnumbers = $query->getQuery()->getResult();
$options = array();
foreach($serialnumbers as $serialnumber){
$options[$serialnumber['serial_nr']] = $serialnumber['serial_nr'];
}
$builder->add("serial_nr","text");
}
It shows the form correctly but when i submit it I get this error:
"The form's view data is expected to be an instance of class Kopict\AdminBundle\Entity\SerialNumber, but is a(n) string. You can avoid this error by setting the "data_class" option to null or by adding a view transformer that transforms a(n) string to an instance of Kopict\AdminBundle\Entity\SerialNumber." at /var/www/kopadmin/vendor/symfony/symfony/src/Symfony/Component/Form/Form.php line 373
This is how my entity looks like:
class SerialNumber
{
/**
* #var integer $id
*/
private $id;
/**
* #var interger $product_revision_id
*/
private $product_revision_id;
/**
* #var interger $booking_id
*/
private $booking_id;
/**
* #var string $serial_nr
*/
public $serial_nr;
/**
* Get id
*
* #return integer
*/
public function getId()
{
return $this->id;
}
/**
* Set product_revision_id
*
* #param integer $product_revision_id
* #return SerialNumber
*/
public function setProduct_revision_id($product_revision_id)
{
$this->product_revision_id = $product_revision_id;
return $this;
}
/**
* Get product_revision_id
*
* #return integer
*/
public function getProduct_revision_id()
{
return $this->product_revision_id;
}
/**
* Set booking_id
*
* #param integer $booking_id
* #return SerialNumber
*/
public function setBooking_id($booking_id)
{
$this->booking_id = $booking_id;
return $this;
}
/**
* Get booking_id
*
* #return integer
*/
public function getBooking_id()
{
return $this->booking_id;
}
/**
* Set serial_nr
*
* #param string $serial_nr
* #return SerialNumber
*/
public function setSerial_nr($serial_nr)
{
$this->serial_nr = $serial_nr;
return $this;
}
/**
* Get serial_nr
*
* #return string
*/
public function getSerial_nr()
{
return $this->serial_nr;
}
}
I have tried to add the data_class but I can't find the good place to add it because the code keeps giving me te same error.

Answer 1

First of all, you need to make your serial_nr private otherwise no need to have getSerial_nr and setSerial_nr functions. Because you can reach to serial_nr outside of your class without having setters and getters.
Second, why you are adding serial numbers into options field?
Assuming you want to have serial numbers as a choice field. I have a solution for you.
Usually entities are related in Doctrine ORM as many-to-one one-to-many. In that case its very simple to get related fields as a choice field. For this case symfony has a built in entity field.
SerialNumberType - form type class. (You have to change this name to yours)
<?php
namespace Kopict\AdminBundle\Form;
use Doctrine\ORM\em;
use Doctrine\ORM\EntityManager;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
class SerialNumberType extends AbstractType
{
private $em;
public function __construct(EntityManager $em)
{
$this->em = $em;
}
public function buildForm(FormBuilderInterface $builder, array $options)
{
$query = $this->em->createQueryBuilder();
$query->select('sn.serial_nr')->from('KopictAdminBundle:SerialNumber', 'sn');
$serialNumbers = $query->getQuery()->getResult();
$choices = array();
foreach ($serialNumbers as $serialNumber) {
$choices[$serialNumber['serial_nr']] = $serialNumber['serial_nr'];
}
$builder->add("serial_nr", "choice", array(
'choices' => $choices,
));
}
public function getName()
{
return 'app_bundle_serial_number_type';
}
}
Inside Controller Action
<?php
namespace Kopict\AdminBundle\Controller;
use Kopict\AdminBundle\Entity\SerialNumber;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
class DefaultController extends Controller
{
public function indexAction()
{
$serialNumber = new SerialNumber();
$form = $this->createForm($this->get('kopict_admin.form.serialnumber'), $serialNumber);
return $this->render('KopictAdminBundle:Default:index.html.twig', array('form' => $form->createView()));
}
}
services.yml
services:
kopict_admin.form.serialnumber:
class: Kopict\AdminBundle\Form\SerialNumberType
arguments: [ #doctrine.orm.entity_manager ]
scope: request