Eccube\Entity\Banner:
    type: entity
    table: dtb_banner
    repositoryClass: Eccube\Repository\BannerRepository
    fields:
        link_method:
            type: smallint
            nullable: false
            unsigned: false
            options:
                default: '0'
    lifecycleCallbacks: {  }

    /**
     * @var integer
     */
    private $link_method;

    /**
     * Set link_method
     *
     * @param  integer $linkMethod
     * @return Banner
     */
    public function setLinkMethod($linkMethod)
    {
        $this->link_method = $linkMethod;

        return $this;
    }

    /**
     * Get link_method
     *
     * @return integer
     */
    public function getLinkMethod()
    {
        return $this->link_method;
    }

class BannerType extends AbstractType
{
    /**
     * {@inheritdoc}
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
         $builder
            ->add('link_method', 'checkbox', array(
                'required' => false,
                'label' => '別ウィンドウを開く',
                'value' => '1',
            ))
        ;
    }

class BannerController extends AbstractController
{
    public function edit(Application $app, Request $request, $id = null)
    {

        $builder = $app['form.factory']
            ->createBuilder('admin_banner', $Banner);
        $form = $builder->getForm();    // ★ ここでエラー発生
    }
}

                    {{ form_row(form.link_method) }}

$transformer = new DataTransformer\IntegerToBooleanTransformer();

$builder
    ->add($builder->create('stock_unlimited', 'checkbox', array(
        'label' => '無制限',
        'value' => '1',
        'required' => false,
    ))->addModelTransformer($transformer));

use Eccube\Form\DataTransformer;

class BannerType extends AbstractType
{
    /**
     * {@inheritdoc}
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {

        $transformer = new DataTransformer\IntegerToBooleanTransformer();

        $builder
            ->add($builder->create('link_method', 'checkbox', array(
                'required' => false,
                'label' => '別ウィンドウを開く',
                'value' => '1',
            ))->addModelTransformer($transformer))
        ;
    }