symfony_form_preset_event_example.php

<?php

use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;
use Symfony\Component\Form\AbstractType;

class MyFormType extends AbstractType
{

	public function buildForm(FormBuilderInterface $builder, array $options)
	{

		// ...

		$builder->addEventListener(FormEvents::PRE_SET_DATA, function (FormEvent $event) {
			$form = $event->getForm();
			$form->add('myField', null, array(
				'data' => $myFieldData,
				// ...

symfony_form_preset_event_example_2.php

<?php

use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;
use Symfony\Component\Form\AbstractType;

class MyFormType extends AbstractType
{

	private $myFieldOptions = array();

	public function buildForm(FormBuilderInterface $builder, array $options)
	{

		// ...

		$form->add('myField', null, array(
			'options' => $this->myFieldOptions,
			// ...

		$builder->addEventListener(FormEvents::PRE_SET_DATA, function (FormEvent $event) {
			$myObject = $event->getData();

			$this->myFieldOptions = ($myObject->isGood() ? array('good', 'super') : array('bad', 'horrible'));

		}