走进Zend Framework框架编程(六)：视图(第三部分)

6.9视图助手(Helper)
视图脚本里经常有一些繁杂的事情，比如格式化日期、产生表单元素等等。这些可以用助手帮我们来完成。
助手类其实是一些以Zend_View_Helper_开头的类，类名的最后一段是助手的名字，助手的名字必须是首字母大写的，该类必须至少有一个以助手名字命名的方法。助手名通常是驼峰式命名，即它不会是大写字母开头的。类名是混合大小写字格式。方法名也是驼峰式命名。
默认的助手的路径通常指向Zend/View/Helper。即使用setHelperPath()方法重新指定了路径，该路径也会保持以使默认的助手能够工作。

6.9.1ZF自带的助手
示例代码：

<?php
    echo $this->form('frm1', array('action'=>'action.php', 'method'=>'post'), false) ."\n";
    echo $this->formHidden('id', 'submited');
    $content = 'Your Name:' . $this->formText('name', '', array('size' => 20)) .'<br>';
    $content .= 'Password:' . $this->formPassword('pass', '', array('size' => 20));
    echo $this->fieldset('flst', $content, array('legend'=>'Name:', 'style'=>'width:200pt')) .'<br>';
 
    echo $this->formLabel('email', 'Your Email:');
    echo $this->formText('email', [email=]'you@example.com'[/email], array('size' => 32)) .'<br>';
    echo 'Your Country:';
    echo $this->formSelect('country', 'us', null, $this->countries) .'<br>';
    echo 'Would you like to opt in?';
    echo $this->formCheckbox('opt_in', 'yes', null, array('yes', 'no')) .'<br>';
    echo 'Choose them:';
    echo $this->formMultiCheckbox('chkbox', 'A', null, array('A'=>'valA','B'=>'valB','C'=>'valC','D'=>'valD'), '<br>') .'<br>';
    echo 'Choose one:';
    echo $this->formRadio('radio', 'A', null, array('A'=>'valA','B'=>'valB','C'=>'valC','D'=>'valD'), '') .'<br>';
    echo $this->htmlList($this->countries) .'<br>';
    echo $this->url(array('k1'=>'v1','k2'=>'v2','k3'=>'v3')) .'<br>';
    echo $this->formTextarea('ta', '', array('rows'=>'5','cols'=>'25')) .'<br>';
    echo $this->formFile('file', '', array()) .'<br>';
    echo $this->formButton('btn', 'BUTTON', array('onClick'=>''));
    echo $this->formSubmit('OK', 'OK');
    echo $this->formReset('reset', 'Reset');
  ?>

6.9.2动作(Action)助手
允许我们在视图脚本里执行某个控制器里的动作方法。
示例：

  <div id="sidebar right">
    <div class="item">
      <?= $this->action('assign1', 'Book'); ?>
    </div>
  </div>

6.9.3区域(Partial)助手
区域助手的基本用法是在它自己的视图范围内解析另一个模板的片段，类似视图脚本嵌套调用。
区域助手的基本用法：
示例：
booklist.php文件包含脚本片段：

<?php
  if ($this->books):
?>
  <table border=1>
  <tr>
    <th>作者</th>
    <th>书名</th>
  </tr>
  <?php
    foreach ($this->books as $key => $val):
  ?>
  <tr>
    <td><?php echo $this->escape($val['author']) ?></td>
    <td><?php echo $this->escape($val['title']) ?></td>
  </tr>
  <?php endforeach; ?>
  </table>
<?php
  else:
?>
  <p>There are no books to display.</p>
<?php
  endif;
?>

在另一个视图脚本通过Partial助手调用booklist.php文件：

<?= $this->partial('booklist.php', array(
  'books' => array(
      array('author'=>'zhangqing','title'=>'《book for php》'),
      array('author'=>'zhangking','title'=>'《book for JSP》'),
      array('author'=>'zhanghing','title'=>'《book for ASP.NET》'),
    )));
?>
<?php echo str_repeat('-', 60). '<br>'; ?>
<?php
  $model = array(
    array('key' => 'Mammal', 'value' => 'Camel'),
    array('key' => 'Bird', 'value' => 'Penguin'),
    array('key' => 'Reptile', 'value' => 'Asp'),
    array('key' => 'Fish', 'value' => 'Flounder'),
  );
?>
<dl>
  <?= $this->partialLoop('partialLoop.phtml', $model) ?>
</dl>

使用 PartialLoop 来解析可迭代的（Iterable）的模型
示例

<?php
  $model = array(
    array('key' => 'Mammal', 'value' => 'Camel'),
    array('key' => 'Bird', 'value' => 'Penguin'),
    array('key' => 'Reptile', 'value' => 'Asp'),
    array('key' => 'Fish', 'value' => 'Flounder'),
  );
?>
<dl>
  <?= $this->partialLoop('partialLoop.phtml', $model) ?>
</dl>

以上代码中partialLoop 调用了以下partialLoop.phtml的内容：

  <dt><?= $this->key ?></dt>
  <dd><?= $this->value ?></dd>

6.9.4占位(Placeholder)助手
示例：

<?= $this->doctype('XHTML1_STRICT') ?>
<?php
// setting meta keywords
$this->headMeta()->appendName('keywords', 'framework php productivity');
$this->headMeta()->appendHttpEquiv('expires', 'Wed, 26 Feb 1997 08:21:57 GMT')
                 ->appendHttpEquiv('pragma', 'no-cache')
                 ->appendHttpEquiv('Cache-Control', 'no-cache');
$this->headMeta()->appendHttpEquiv('Content-Type', 'text/html; charset=UTF-8')
                 ->appendHttpEquiv('Content-Language', 'en-US');
$this->headMeta()->appendHttpEquiv('Refresh', '3;URL=http://www.some.org/some.html');
echo $this->headMeta();
$this->headScript()->appendFile('/js/prototype.js')
                   ->appendScript('xx.js');
// Putting scripts in order
// place at a particular offset to ensure loaded last
$this->headScript()->offsetSetScript(100, '/js/myfuncs.js');
// use scriptaculous effects (append uses next index, 101)
$this->headScript()->appendScript('/js/scriptaculous.js');
// but always have base prototype script load first:
$this->headScript()->prependScript('/js/prototype.js');
echo $this->headScript();
// setting links in a view script:
$this->headLink()->appendStylesheet('/styles/basic.css')
                 ->headLink(array('rel' => 'favicon', 'href' => '/img/favicon.ico'), 'PREPEND')
                 ->prependStylesheet('/styles/moz.css', 'screen', true);
// rendering the links:
echo $this->headLink();
?>
<?php
  $this->placeholder('foo')->setPrefix("<ul>\n<li>")
                           ->setSeparator("</li><li>\n")
                           ->setIndent(4)
                           ->setPostfix("</li></ul>\n");
  $this->placeholder('foo')->set("Some text for later-1");
  $this->placeholder('foo')->bar = "Some text for later-2";
  echo $this->placeholder('foo');
  $foo = $this->placeholder('foo');
  echo $foo[0] .'<br>';
  echo $foo['bar'] .'<br>';
?>
<!-- Default capture: append -->
<?php
  $this->placeholder('hoo')->captureStart();
  foreach ($this->data as $datum)
  {
?>
  <div class="hoo">
    <h2><?= $datum['title'] ?></h2>
    <p><?= $datum['content'] ?></p>
  </div>
<?php
  }
  $this->placeholder('hoo')->captureEnd();
?>
<?php
  echo $this->placeholder('hoo')
?>
<!-- Capture to key -->
<?php
  $this->placeholder('woo')->captureStart('SET', 'data');
  foreach ($this->data as $datum):
?>
  <div class="woo">
    <h2><?= $datum['title'] ?></h2>
    <p><?= $datum['content'] ?></p>
</div>
<?php
  endforeach;
  $this->placeholder('woo')->captureEnd();
?>
<?php
  echo $this->placeholder('woo')->data;
?>

6.9.4自定义助手
编写及调用自定义助手的方法：
The class name must, at the very minimum, end with the helper name itself, using MixedCaps. E.g., if you were writing a helper called "specialPurpose", the class name would minimally need to be "SpecialPurpose". You may, and should, give the class name a prefix, and it is recommended that you use 'View_Helper' as part of that prefix: "My_View_Helper_SpecialPurpose". (You will need to pass in the prefix, with or without the trailing underscore, to addHelperPath() or setHelperPath()).
The class must have a public method that matches the helper name; this is the method that will be called when your template calls "$this->specialPurpose()". In our "specialPurpose" helper example, the required method declaration would be "public function specialPurpose()".
In general, the class should not echo or print or otherwise generate output. Instead, it should return values to be printed or echoed. The returned values should be escaped appropriately.
The class must be in a file named after the helper class. Again using our "specialPurpose" helper example, the file has to be named "SpecialPurpose.php".
Place the helper class file somewhere in your helper path stack, and Zend_View will automatically load, instantiate, persist, and execute it for you.
示例：

<?php
  //Custom Helper "myFieldset"
  echo $this->myFieldset('This my custom Helper.').'<br>';
  echo $this->myFieldset('This my custom Helper.').'<br>';
  echo $this->myFieldset('This my custom Helper.').'<br>';
?>

调用代码：

    function customhelperAction()
    {
      $view = new Zend_View();
      $view->setScriptPath('views');
      $view->setHelperPath('views/helpers', 'My_View_Helper');
      echo $view->render('my_custom_helper.php');
    }

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