Pass data from entity form to controller Symfony3 - symfony

Question

I have entity type class field (dropdown) which generate data from one of my table. I have form sub-agent where user will select a company for that particular sub-agent.
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder->add('company_id', EntityType::class, array(
'label' => 'Company',
'required' => true,
'class' => 'OnlyBundle\Entity\Company',
'choice_label' => 'name', // The Company Name
'choice_value' => 'id', // The Company ID (unique) to be inserted in DB
'expanded' => false,
'multiple' => false,
'placeholder' => 'Choose a Company',
'constraints' => array(
new NotBlank(array("message" => 'Company name is required.')),
),
));
This entity will generate twig like below.
<select id="sub_agent_company_id" name="sub_agent[company_id]" required="required">
<option value="" selected="selected">Choose a Company</option>
<option value="20">ABC</option>
<option value="21">EFG</option>
<option value="22">HIJ</option>
</select>
I want to pass or set the value of dropdown field (20, 21, 22) into my controller, but the problem is, the drop down returns an object from my company class. How do I pass only the value of dropdown and not the whole controller?
Here's my controller.
public function createAction(Request $request) {
$sub_agent = new Sub_agent;
$form = $this->createForm(SubAgentType::class, $sub_agent, array(
'action'=>$this->generateUrl('swipe_backend_sub_agent_create'),
'method'=>'POST'
));
$form->handleRequest($request);
if ('POST' === $request->getMethod()) {
$data = $form->getData();
$sub_agent_name = $data->getName();
var_dump($data->getCompanyId()); exit;
..../

Answer 1

$data->getCompanyId() returns company object. If you want only get its id instead of whole object just call $data->getCompanyId()->getId()

Answer 2

You can get the company's id in the controller, directly from the form with:
$id = $sub_agent->getId();
...assuming you have a getter in your Sub_agent entity class
public function getId(){
return $this->id;
}
But you're missing the whole point here. When you work with Doctrine, forget about "SQL's way", and instead think the whole problem as objects.
Just drop that if ('POST' === $request->getMethod()) and instead add:
if ($form->isSubmitted() && $form->isValid()) {
...
}
which checks if the form was submitted and if it's valid, according to your constraints, set up in the Sub_agent entity, if any.
And in that check I've told you to add, just dump the $sub_agent variable to see what's inside. Don't forget the first thing: in the template you have the corresponding form, add some data you want, and submit that form, then check the dump from the controller.
//...
if ($form->isSubmitted() && $form->isValid()) {
dump($sub_agent); die;
}
So the whole point is that you don't need to worry, or to try to get each individual field from the form, and then to map them to the entity's properties, to be able to save the form data in the database. Doctrine is already doing that for you. All you need to do is to set up the entity (properties + getters and setters), create the form based on that entity, and then add the code I've told you. That's it! Easy enough?