Persisting entity with relation and form data - symfony

Question

I have the AppBundle\Entity\Comments entity which I want to persist to the database when the user fill the form I can't find information exactly how to save the form data to the database:
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity
* #ORM\Table(name="Comments")
*/
class Comments
{
/**
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #ORM\ManyToOne(targetEntity="Employer")
* #ORM\JoinColumn(name="employer_id", referencedColumnName="id")
*/
private $employer;
/**
* #ORM\ManyToOne(targetEntity="Application\Sonata\UserBundle\Entity\User")
* #ORM\JoinColumn(name="company_id", referencedColumnName="id")
*/
private $company;
/**
* #ORM\ManyToOne(targetEntity="Commenttypes")
* #ORM\JoinColumn(name="comment_id", referencedColumnName="id")
*/
private $comment;
/**
* #ORM\Column(type="date")
*/
private $from_date;
/**
* #ORM\Column(type="date")
*/
private $to_date;
?>
Here is the Form Type:
<?
namespace AppBundle\Form\Type;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\Extension\Core\Type\SubmitType;
use Symfony\Component\OptionsResolver\OptionsResolver;
class WorkerType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('comment', 'entity', array(
'class' => 'AppBundle\Entity\CommentTypes',
'label' => 'Comment:'
))
->add('from_date', 'Symfony\Component\Form\Extension\Core\Type\DateType', array(
'label' => 'From date:',
'input' => 'datetime',
'widget' => 'single_text',
'format' => 'dd-MM-yyyy',
'attr' => [ 'class' => 'datepicker' ]
))
->add('to_date', 'Symfony\Component\Form\Extension\Core\Type\DateType', array(
'label' => 'To date:',
'input' => 'datetime',
'widget' => 'single_text',
'format' => 'dd-MM-yyyy',
'attr' => [ 'class' => 'datepicker' ]
))
->add('submit', 'Symfony\Component\Form\Extension\Core\Type\SubmitType', array(
'label' => 'Submit',
'attr' => [ 'class' => 'buttonColor' ]
));
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'data_class' => 'AppBundle\Entity\Comments',
));
}
}
?>
So by now, I'm receiving the data for the fields $from_date and $to_date and $comment (the ID of the comment from the dropdown) from the Form, what I need to to in my controller in order to persist the comment object to the database. Here is my controller:
<?php
namespace AppBundle\Controller;
use AppBundle\Entity\Comments;
use AppBundle\Form\Type\WorkerType;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Request;
class Worker extends Controller
{
/**
* #Route("/worker/{id}", name="worker")
*/
public function indexAction($id, Request $request)
{
$comment = new Comments();
$form = $this->createForm('AppBundle\Form\Type\WorkerType', $comment);
$form->handleRequest($request);
if ($form->isSubmitted() && $form->isValid()) {
{{{{ CODE HERE }}}}
}
return $this->render('default/worker.html.twig',array(
'form' => $form->createView()
));
}
}
I exactly want to know what I need to do to persist the comment object if the form is valid, I'm trying with this:
if ($form->isSubmitted() && $form->isValid()) {
$comment->setEmployer($id);
$comment->setCompany($this->getUser());
$comment->setComment($form->get('comment')->getData());
$comment->setfrom_date($form->get('from_date')->getData());
$comment->setto_date($form->get('to_date')->getData());
}
But I get this error:
Catchable Fatal Error: Argument 1 passed to AppBundle\Entity\Comments::setEmployer() must be an instance of AppBundle\Entity\Employer, string given, called in /home1/rabotnici/src/AppBundle/Controller/Worker.php on line 42 and defined