如何在Symfony 2.1的FormEvent中更新ChoiceType的值？

Question

我想我可能需要延長LazyChoiceList和實施新的FormType，所以到目前爲止，我有：

/** 
* A choice list for sorting choices. 
*/ 
class SortChoiceList extends LazyChoiceList 
{ 
    private $choices = array(); 

    public function getChoices() { 
     return $this->choices; 
    } 

    public function setChoices(array $choices) { 
     $this->choices = $choices; 
     return $this; 
    } 

    protected function loadChoiceList() { 
     return new SimpleChoiceList($this->choices); 
    } 
} 

和

/** 
* @FormType 
*/ 
class SortChoice extends AbstractType 
{ 
    public function buildForm(FormBuilderInterface $builder, array $options) 
    { 
     $builder->getParent()->addEventListener(FormEvents::PRE_SET_DATA, function($event) use ($options) { 
      $options = (object) $options; 

      $list = $options->choice_list; 

      $data = $event->getData(); 

      if ($data->getLocation() && $data->getDistance()) { 
       $list->setChoices(array(
        '' => 'Distance', 
        'highest' => 'Highest rated', 
        'lowest' => 'Lowest rated' 
       )); 
      } else { 
       $list->setChoices(array(
        '' => 'Highest rated', 
        'lowest' => 'Lowest rated' 
       )); 
      } 
     }); 
    } 

    public function getParent() 
    { 
     return 'choice'; 
    } 

    public function getName() 
    { 
     return 'sort_choice'; 
    } 

    public function setDefaultOptions(OptionsResolverInterface $resolver) 
    { 
     $resolver->setDefaults(array(
      'choice_list' => new SortChoiceList 
     )); 
    } 
} 

我試過這種方法對所有的可用的FormEvent的，但我沒有訪問數據（空值）或更新choice_list沒有效果，據我所知，因爲它已經被處理。

Answer 1

原來我並不需要在所有定義一個新類型或LazyList和更好的做法是，直到我有數據，在我的主要形式，像這樣不加場：

$builder->addEventListener(FormEvents::PRE_BIND, function($event) use ($builder) { 
    $form = $event->getForm(); 
    $data = (object) array_merge(array('location' => null, 'distance' => null, 'sort_by' => null), $event->getData()); 

    if ($data->location && $data->distance) { 
     $choices = array(
      '' => 'Distance', 
      'highest' => 'Highest rated', 
      'lowest' => 'Lowest rated' 
     ); 
    } else { 
     $choices = array(
      '' => 'Highest rated', 
      'lowest' => 'Lowest rated' 
     ); 
    } 

    $form->add($builder->getFormFactory()->createNamed('sort_by', 'choice', $data->sort_by, array(
     'choices' => $choices, 
     'required' => false 
    ))); 
}); 

見：http://symfony.com/doc/master/cookbook/form/dynamic_form_generation.html

Answer 2

你讀過這個：http://symfony.com/doc/master/cookbook/form/dynamic_form_generation.html

的例子有：

if (!$data) return; 

而這是因爲這些事件似乎在窗體被構建時被多次觸發。我在您的發佈代碼中沒有看到相應的行。