Symfony2: adding form fields dynamically using information from request - symfony

Question

Scenario:
step 1: fetch information from some archaic web service
step 2: adding x radio buttons to my form, while x depends on the information from the web service
I understand that I should add an Event Subscriber Class as shown in the documentation
$event has a setData method. Probably I have to use it. How can I access this method from the controller?
Additional information:
I am using Doctrine. At the moment I am creating a Doctrine entity and pass this to the form like this:
$product = new Product(); $form = $this->createForm(new ProductType(), $product);

Answer 1

This is my solution I ended up with. Not sure if this is the best way, so this answer is not marked as correct to encourage other, more experience Symfony user to come up with a better solution.
What I don't like about this solution, is that I cannot pass my whole product entity to the form any more, but have to add each attribute individually to the options array:
Anyway, that's how it is implemented now:
The dynamic data is passed using the options array as second parameter to createForm():
// ExampleController.php
use Acme\ExampleBundle\Entity\Product;
public function addAction()
{
// choices contains the dynamic data I am fetching from the webservice in my actual code
$choices = array("key1" => "value1", "key2" => "value2");
// now create a new Entity
$product = new Product();
// and some attributes already have values for some reason
$product->setPrice(42);
$form = $this->createForm(new AddproductType(),
array(
"choices" => $choices,
"price" => $product->getPrice()
)
);
if ($request->isMethod('POST')) {
$form->bind($request);
if ($form->isValid()) {
// ... standard symfony stuff here
}
}
return array(
'form' => $form->createView()
);
}
And now for the form class. Note the event listener part and the setDefaultOptions method.
// ProductType.php
namespace Acme\ExampleBundle\Form;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormEvents;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
class ProductType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$formFactory = $builder->getFormFactory();
$builder->addEventListener(
FormEvents::PRE_SET_DATA,
function (\Symfony\Component\Form\FormEvent $event) use ($formFactory) {
// get the option array passed from the controller
$options = $event->getData();
$choices = $options["choices"];
$event->getForm()->add(
// add a new element with radio buttons to the form
$formFactory->createNamed("my_dynamic_field_name", "choice", null, array(
"empty_value" => "Choose an option",
"label" => "My dynamic field: ",
"choices" => $choices
)
)
);
}
);
// ... add other form elements
$builder->add("price", "text");
// ..
}
public function setDefaultOptions(OptionsResolverInterface $resolver)
{
// register choices as a potential option
$resolver->setDefaults(array(
'choices' => null
));
}
}

Answer 2

You don't have to setData() on the $event object. You've to implement an on POST_SET_DATA logic that builds your form the way you want according to you data.
You've then to initialize your form (inside your controller) using your webservice's reply.
(Note: SET_DATA form event is deprecated since version 2.1. It'll be definitely removed in version 2.3)
Update:
You can set an array as form data and use a DataTransformer to structure your form's data the way you want. Take a look at the Data Transformation part of Symfony 2 Form Tricks during the last San Francisco Symfony Live.