php - 表单规范数据与 View 数据——有什么区别？

Question

The documentation说:

In any form, the three different types of data are:

    Model data - This is the data in the format used in your application (e.g. an Issue object). If you call Form::getData() or Form::setData(), you're dealing with the "model" data.
    Norm Data - This is a normalized version of your data and is commonly the same as your "model" data (though not in our example). It's not commonly used directly.
    View Data - This is the format that's used to fill in the form fields themselves. It's also the format in which the user will submit the data. When you call Form::submit($data), the $data is in the "view" data format.

但是我不明白常模数据和 View 数据的区别。常模数据的用例是什么？文档的下一段 "So why Use the Model Transformer?"对我来说没有任何意义。

Answer 1

我找到的最好的解释是在 Symfony 的 Form 类描述中:

<?php

...

namespace Symfony\Component\Form;

use ...

/**
 * Form represents a form.
 *
 * To implement your own form fields, you need to have a thorough understanding
 * of the data flow within a form. A form stores its data in three different
 * representations:
 *
 *   (1) the "model" format required by the form's object
 *   (2) the "normalized" format for internal processing
 *   (3) the "view" format used for display
 *
 * A date field, for example, may store a date as "Y-m-d" string (1) in the
 * object. To facilitate processing in the field, this value is normalized
 * to a DateTime object (2). In the HTML representation of your form, a
 * localized string (3) is presented to and modified by the user.
 *
 * In most cases, format (1) and format (2) will be the same. For example,
 * a checkbox field uses a Boolean value for both internal processing and
 * storage in the object. In these cases you simply need to set a value
 * transformer to convert between formats (2) and (3). You can do this by
 * calling addViewTransformer().
 *
 * In some cases though it makes sense to make format (1) configurable. To
 * demonstrate this, let's extend our above date field to store the value
 * either as "Y-m-d" string or as timestamp. Internally we still want to
 * use a DateTime object for processing. To convert the data from string/integer
 * to DateTime you can set a normalization transformer by calling
 * addNormTransformer(). The normalized data is then converted to the displayed
 * data as described before.
 *
 * The conversions (1) -> (2) -> (3) use the transform methods of the transformers.
 * The conversions (3) -> (2) -> (1) use the reverseTransform methods of the transformers.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 * @author Bernhard Schussek <bschussek@gmail.com>
 */
class Form implements \IteratorAggregate, FormInterface
{
    ...
}

编辑:这是来自 Sf 表单组件(合)作者的视频，他在其中解释了数据格式并给出了规范化格式使用的示例 -> https://youtu.be/Q80b9XeLUEA?t=7m6s

---

所以，基本上，每个表单都有三种不同格式的数据。前两个是:模型数据 - 您在领域模型中使用的数据，以及 View 数据 - 您通常在 HTML 中输出为字符串或在提交前输入表单字段的数据。

两个简单的示例是 TextType 和 NumberType。在TextType中，模型数据是字符串， View 数据是字符串。

在 NumberType 中，模型数据是一个 float - 在您的应用程序中，您处理的是 float 类型，而 View 数据是本地化的字符串。

但是，另一方面，如果我们看一下 DateType，事情会有点复杂，因为模型数据可能是字符串 ('YYYY-MM-DD')、整数(unix 时间戳)，数组或 DateTime 对象。 View 数据可以是本地化的字符串或数组。

例如，如果你想写一个事件监听器，你不能确定你会得到什么数据格式:

class MyDateType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add...
            ->addEventListener(
                FormEvents::FormEvents::SUBMIT,
                array($this, 'onSubmit')
            )
        ;
    }

    public function onSubmit(FormEvent $event)
    {
        // BUT WHAT FORMAT DO I GET???
        $data = $event->getForm()->getData();
    }
}

幸运的是，Sf form还有第三种数据格式——归一化格式。该格式是静态的 - 您始终知道会得到什么，它始终是相同的数据类型!

 public function onSubmit(FormEvent $event)
 {
     // $data will be DateTime object!
     $data = $event->getForm()->getNormData();
 }