Symfony2表单类型实体添加额外选项

我有以下 Symfony 表单字段，它是从实体加载的下拉列表：

->add('measureunit', 'entity', array('label' => 'Measure Unit',
            'class' => 'TeamERPBaseBundle:MeasureUnit',
            'expanded' => false, 'empty_value' => '',
            'multiple' => false, 'property' => 'abreviation'
        ))

正如你所看到的，我已经添加了'empty_value' => ''一切正常。现在，我想要的是在最后有一个额外的选项来添加一个比方说new measure unit。换句话说，下拉列表应该显示我的实体的所有内容、空值和其他称为new measure unit或者我想怎么称呼它。是否可以？

Edit:整个表单类型文件有这样的：

<?php
namespace TeamERP\StoresBundle\Form\Type;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
class ProductType  extends AbstractType 
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
        ->add('name', 'text', array('label'=>'Product name', 'required' => true,
        'attr' => array('class' => 'form-control')))
        ->add('code', 'text', array('label'=>'Code', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('description', 'text', array('label'=>'Description', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('cost', 'money', array('label'=>'Cost', 'divisor' => 100, 'currency' => 'BWP'))
        ->add('category', new CategoryType(), array('required' => false))
        ->add('measureunit', 'entity', array('label' => 'Measure Unit',
            'class' => 'TeamERPBaseBundle:MeasureUnit',
            'expanded' => false, 'placeholder' => '',
            'multiple' => false, 'property' => 'abreviation'
        ))
        ->add('qtyToPurchase', 'number', array('label'=>'Quantity to purchase', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('reorderPoint', 'number', array('label'=>'Reorder point', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('qtyOnSalesOrder', 'number', array('label'=>'Quantity on sales order', 'required' => false,
        'attr' => array('class' => 'form-control')));
    }
public function getName()
    {
        return 'product';
    }
public function finishView(FormView $view, FormInterface $form, array $options)
    {
        $new_choice = new ChoiceView(array(), 'add', 'add new'); // <- new option
        $view->children['measureunit']->vars['choices'][] = $new_choice;//<- adding the new option 
    }
}

Error: Compile Error: Declaration of TeamERP\StoresBundle\Form\Type\ProductType::finishView() must be compatible with Symfony\Component\Form\FormTypeInterface::finishView(Symfony\Component\Form\FormView $view, Symfony\Component\Form\FormInterface $form, array $options)

Edit2工作表格文件：

<?php
namespace TeamERP\StoresBundle\Form\Type;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\FormView; 
use Symfony\Component\Form\FormInterface;
use Symfony\Component\Form\Extension\Core\View\ChoiceView;
class ProductType  extends AbstractType 
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
        ->add('name', 'text', array('label'=>'Product name', 'required' => true,
        'attr' => array('class' => 'form-control')))
        ->add('code', 'text', array('label'=>'Code', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('description', 'text', array('label'=>'Description', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('cost', 'money', array('label'=>'Cost', 'divisor' => 100, 'currency' => 'BWP'))
        ->add('category', new CategoryType(), array('required' => false))
        ->add('measureunit', 'entity', array('label' => 'Measure Unit',
            'class' => 'TeamERPBaseBundle:MeasureUnit',
            'expanded' => false, 'placeholder' => '',
            'multiple' => false, 'property' => 'abreviation'
        ))
        ->add('qtyToPurchase', 'number', array('label'=>'Quantity to purchase', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('reorderPoint', 'number', array('label'=>'Reorder point', 'required' => false,
        'attr' => array('class' => 'form-control')))
        ->add('qtyOnSalesOrder', 'number', array('label'=>'Quantity on sales order', 'required' => false,
        'attr' => array('class' => 'form-control')));
    }
public function getName()
    {
        return 'product';
    }
public function finishView(FormView $view, FormInterface $form, array $options)
    {
        $new_choice = new ChoiceView(array(), 'add', 'add new'); // <- new option
        $view->children['measureunit']->vars['choices'][] = $new_choice;//<- adding the new option 
    }
}

在您的表单中键入覆盖该函数finishView http://api.symfony.com/3.2/Symfony/Component/Form/Extension/Core/Type/TimezoneType.html#method_finishView:

public function buildForm(FormbuilderInterface $builder, array $options){
    $builder->add('measureunit', EntityType::class, array(
        'label' => 'Measure Unit',
        'class' => 'TeamERPBaseBundle:MeasureUnit',
        'expanded' => false, 
        'empty_value' => '',
        'multiple' => false, 
        'property' => 'abbreviation'
    ));
}

public function finishView(FormView $view, FormInterface $form, array $options)
{
    $newChoice = new ChoiceView(array(), 'add', 'Add New'); // <- new option
    $view->children['measureunit']->vars['choices'][] = $newChoice;//<- adding the new option 
}

您将在字段底部看到一个新选项“添加新”，其值为“添加”。