我从symfony 2开始，我想显示一个"选择"类型的数据库中的数据，但我有一个问题：
添加操作：

public function addAction()
{
    $categories = new CategoriesAnnonce();
    $form = $this->get('form.factory')->create(new AddFormType($categories),$categories);
    return $this->render('AnnoncesBundle::add.html.twig', array(
        'form' => $form->createView(),
    ));
}

添加表单类型. php：

<?php

namespace AnnoncesBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Symfony\Component\Validator\Constraints as Assert;

class AddFormType extends AbstractType
{
    private $cat;

    public function __construct(CategoriesAnnonce $categories)
    {
        $this->cat = $categories->getNomSousCategorie();
    }

    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('titre', 'text')
            ->add('categories', 'choice', array(
            'choices' => $this->cat,
        ));
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'AnnoncesBundle\Form\Model\Add',
        ));
    }

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

?>

错误：

Catchable Fatal Error: Argument 1 passed to AnnoncesBundle\Form\Type\AddFormType::__construct() must be an instance of AnnoncesBundle\Form\Type\CategoriesAnnonce, instance of AnnoncesBundle\Entity\CategoriesAnnonce given, called in /Users/jordan/Desktop/www/Lesbonnesaffaires/src/AnnoncesBundle/Controller/DefaultController.php on line 69 and defined