Symfony2CookBook：如何使用虚拟的表单域选项

• 原文出处：http://symfony.com/doc/2.1/cookbook/form/use_virtuals_forms.html
• 原文作者：symfony.com
• 授权许可：创作共用协议
• 翻译人员：FireHare
• 校对人员：FireHare
• 适用版本：Symfony 2.1
• 文章状态：草译阶段

The virtual form field option can be very useful when you have some duplicated fields in different entities.
当您在不同的实体中拥有一些重复的表单域时，虚拟表单域选项就显得非常有用。

For example, imagine you have two entities, a Company and a Customer:
举个例子，想象您有两个实体，Company和Customer：

Company实体：

// src/Acme/HelloBundle/Entity/Company.php
namespace Acme\HelloBundle\Entity;

class Company
{
    private $name;
    private $website;

    private $address;
    private $zipcode;
    private $city;
    private $country;
}

 Customer实体：

// src/Acme/HelloBundle/Entity/Customer.php
namespace Acme\HelloBundle\Entity;

class Customer
{
    private $firstName;
    private $lastName;

    private $address;
    private $zipcode;
    private $city;
    private $country;
}

Like you can see, each entity shares a few of the same fields: address, zipcode, city, country.
正如您所见，每个实体都有着一些相同的表单域：address、zipcode、city和country。

Now, you want to build two forms: one for a Company and the second for a Customer.
现在，您要创建两个表单：一个对应Company，第二个对应Customer。

Start by creating a very simple CompanyType and CustomerType:
首先创建一个非常简单的CompanyType和CustomerType：

CompanyType类：

// src/Acme/HelloBundle/Form/Type/CompanyType.php
namespace Acme\HelloBundle\Form\Type;

use Symfony\Component\Form\FormBuilderInterface;

class CompanyType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('name', 'text')
            ->add('website', 'text');
    }
}

 CustomerType类：

// src/Acme/HelloBundle/Form/Type/CustomerType.php
namespace Acme\HelloBundle\Form\Type;

use Symfony\Component\Form\FormBuilderInterface;

class CustomerType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('firstName', 'text')
            ->add('lastName', 'text');
    }
}

Now, we have to deal with the four duplicated fields. Here is a (simple) location form type:
现在我们需要处理那四个重复的表单域。下面是个（简单）的位置表单类型：

// src/Acme/HelloBundle/Form/Type/LocationType.php
namespace Acme\HelloBundle\Form\Type;

use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class LocationType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('address', 'textarea')
            ->add('zipcode', 'text')
            ->add('city', 'text')
            ->add('country', 'text');
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'virtual' => true
        ));
    }

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

We don't actually have a location field in each of our entities, so we can't directly link our LocationType to our CompanyType or CustomerType. But we absolutely want to have a dedicated form type to deal with location (remember, DRY!).
实际上在每个实体中我们并没有location表单域，因此我们不能直接将LocationType链入我们的CompanyType或CustomerType中。但我们又绝对想要一个专门处理位置的表单类型（记住，DRY！）

The virtual form field option is the solution.
解决这个问题就需要用到虚拟表单域选项了。

We can set the option 'virtual' => true in the setDefaultOptions() method of LocationType and directly start using it in the two original form types.
我们可以在LocationType类中的setDefaultOptions()方法中将选项'virtual'设置为true，并且在两个原始域类型中直接使用它。

Look at the result:
所下所示：

CompanyType类：

// CompanyType
public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder->add('foo', new LocationType(), array(
        'data_class' => 'Acme\HelloBundle\Entity\Company'
    ));
}

 CustomerType类：

// CustomerType
public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder->add('bar', new LocationType(), array(
        'data_class' => 'Acme\HelloBundle\Entity\Customer'
    ));
}

With the virtual option set to false (default behavior), the Form Component expects each underlying object to have a foo (or bar) property that is either some object or array which contains the four location fields. Of course, we don't have this object/array in our entities and we don't want it!
当virtual选项设为false时（缺省值），表单组件期望每个相关的对象都有一个foo（或bar）属性，要么是一些对象，要么是包含四个位置表单域的数组。当然，在我们的实体中没有这样的对象或数组，而且我们也不想那样做！

With the virtual option set to true, the Form component skips the foo (or bar) property, and instead "gets" and "sets" the 4 location fields directly on the underlying object!
当virtual选项设为true时，表单组件忽略foo（或bar）属性，取而代之的是在相关对象中直接"gets"和"sets"这4个位置表单域！

Instead of setting the virtual option inside LocationType, you can (just like with any options) also pass it in as an array option to the third argument of $builder->add(). 如果不使用在LocationType中设置virtual选项，您也可以（如其它选项那样）将其作为一个数组选项发送到$builder->add()的第三个参数。