Detailed explanation of usage of Zend Framework Action Assistant (Zend_Controller_Action_Helper), zendhelper

Detailed explanation of the usage of Zend Framework Action Assistant (Zend_Controller_Action_Helper), zendhelper

This article describes the usage of Zend Framework Action Assistant (Zend_Controller_Action_Helper) with examples. Share it with everyone for your reference, the details are as follows:

Through the assistant mode, some frequently used functional modules can be encapsulated, so that they can be used flexibly where needed, mainly in actions.

There are two kinds of helpers in Zend Framework, action assistant (Zend_Controller_Action_Helper) and view assistant (Zend_View_Helper).

The action assistant can instantly add functions (runtime and/or on-demand functionality) to any derived action controller of Zend_Controller_Action, so that when adding public action controller functions, the number of derived action controller classes can be minimized. necessary.

The action helper is loaded when it needs to be called, and can be instantiated when requested (bootstrap) or when the action controller is created (init()).

Relevant documents involved

In /library/Zend/Controller/Action/

│ Exception.php
│ HelperBroker.php
│Interface.php
│
├─Helper
│ │ Abstract.php
│ │ ActionStack.php
│ │ AjaxContext.php
│ │ AutoCompleteDojo.php
│ │ AutoCompleteScriptaculous.php
│ │ Cache.php
│ │ ContextSwitch.php
│ │ FlashMessenger.php
│ │ Json.php
│ │ Redirector.php
│ │ Url.php
│ │ ViewRenderer.php
│ │
│ └─AutoComplete
│ Abstract.php
│
└─HelperBroker
PriorityStack.php

Common action assistants include :

FlashMessenger is used to handle Flash Messenger sessions;
Json is used to decode and send JSON responses;
Url is used to create Urls;
Redirector provides another implementation method to help the program redirect to internal or external pages;
ViewRenderer automatically completes the process of establishing a view object in the controller and rendering the view;
AutoComplete automatically responds to AJAX autocomplete;
ContextSwitch and AjaxContext provide alternative response formats for your actions;
Cache implements cache related operations;
ActionStack is used to operate the action stack.

A few hands-on ways to use instantiation

1. Through the getHelper() method of the $_helper member of Zend_Controller_Action . Just call getHelper() directly and pass in the name of the helper.

$redirector = $this->_helper->getHelper('Redirector');
//$redirector->getName();
$redirector->gotoSimple('index2');

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2. Directly access the helper object corresponding to the attribute of the _helper assistant.

$redirector = $this->_helper->Redirector;

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Zend_Controller_Action_HelperBroker

The Chinese name is translated as "Assistant Broker", as the name suggests, it is the middleman of the action assistant.

The second way to instantiate an action is through the magic method __get() of Zend_Controller_Action_HelperBroker.

The assistant broker is used to register assistant objects and assistant paths, obtain assistants and other functions.

Zend_Controller_Action_HelperBroker implementation and list of common methods

<&#63;php
/**
 * @see Zend_Controller_Action_HelperBroker_PriorityStack
 */
require_once 'Zend/Controller/Action/HelperBroker/PriorityStack.php';
/**
 * @see Zend_Loader
 */
require_once 'Zend/Loader.php';
/**
 * @category  Zend
 * @package  Zend_Controller
 * @subpackage Zend_Controller_Action
 * @copyright Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license  http://framework.zend.com/license/new-bsd   New BSD License
 */
class Zend_Controller_Action_HelperBroker
{
  /**
   * $_actionController - ActionController reference
   *
   * @var Zend_Controller_Action
   */
  protected $_actionController;
  /**
   * @var Zend_Loader_PluginLoader_Interface
   */
  protected static $_pluginLoader;
  /**
   * $_helpers - Helper array
   *
   * @var Zend_Controller_Action_HelperBroker_PriorityStack
   */
  protected static $_stack = null;
  /**
   * Set PluginLoader for use with broker
   *
   * @param Zend_Loader_PluginLoader_Interface $loader
   * @return void
   */
  public static function setPluginLoader($loader)
  {
    if ((null !== $loader) && (!$loader instanceof Zend_Loader_PluginLoader_Interface)) {
      require_once 'Zend/Controller/Action/Exception.php';
      throw new Zend_Controller_Action_Exception('Invalid plugin loader provided to HelperBroker');
    }
    self::$_pluginLoader = $loader;
  }
  /**
   * Retrieve PluginLoader
   *
   * @return Zend_Loader_PluginLoader
   */
  public static function getPluginLoader()
  {
    if (null === self::$_pluginLoader) {
      require_once 'Zend/Loader/PluginLoader.php';
      self::$_pluginLoader = new Zend_Loader_PluginLoader(array(
        'Zend_Controller_Action_Helper' => 'Zend/Controller/Action/Helper/',
      ));
    }
    return self::$_pluginLoader;
  }
  /**
   * addPrefix() - Add repository of helpers by prefix
   *
   * @param string $prefix
   */
  static public function addPrefix($prefix)
  {
    $prefix = rtrim($prefix, '_');
    $path  = str_replace('_', DIRECTORY_SEPARATOR, $prefix);
    self::getPluginLoader()->addPrefixPath($prefix, $path);
  }
  /**
   * addPath() - Add path to repositories where Action_Helpers could be found.
   *
   * @param string $path
   * @param string $prefix Optional; defaults to 'Zend_Controller_Action_Helper'
   * @return void
   */
  static public function addPath($path, $prefix = 'Zend_Controller_Action_Helper')
  {
    self::getPluginLoader()->addPrefixPath($prefix, $path);
  }
  /**
   * addHelper() - Add helper objects
   *
   * @param Zend_Controller_Action_Helper_Abstract $helper
   * @return void
   */
  static public function addHelper(Zend_Controller_Action_Helper_Abstract $helper)
  {
    self::getStack()->push($helper);
    return;
  }
  /**
   * resetHelpers()
   *
   * @return void
   */
  static public function resetHelpers()
  {
    self::$_stack = null;
    return;
  }
  /**
   * Retrieve or initialize a helper statically
   *
   * Retrieves a helper object statically, loading on-demand if the helper
   * does not already exist in the stack. Always returns a helper, unless
   * the helper class cannot be found.
   *
   * @param string $name
   * @return Zend_Controller_Action_Helper_Abstract
   */
  public static function getStaticHelper($name)
  {
    $name = self::_normalizeHelperName($name);
    $stack = self::getStack();
    if (!isset($stack->{$name})) {
      self::_loadHelper($name);
    }
    return $stack->{$name};
  }
  /**
   * getExistingHelper() - get helper by name
   *
   * Static method to retrieve helper object. Only retrieves helpers already
   * initialized with the broker (either via addHelper() or on-demand loading
   * via getHelper()).
   *
   * Throws an exception if the referenced helper does not exist in the
   * stack; use {@link hasHelper()} to check if the helper is registered
   * prior to retrieving it.
   *
   * @param string $name
   * @return Zend_Controller_Action_Helper_Abstract
   * @throws Zend_Controller_Action_Exception
   */
  public static function getExistingHelper($name)
  {
    $name = self::_normalizeHelperName($name);
    $stack = self::getStack();
    if (!isset($stack->{$name})) {
      require_once 'Zend/Controller/Action/Exception.php';
      throw new Zend_Controller_Action_Exception('Action helper "' . $name . '" has not been registered with the helper broker');
    }
    return $stack->{$name};
  }
  /**
   * Return all registered helpers as helper => object pairs
   *
   * @return array
   */
  public static function getExistingHelpers()
  {
    return self::getStack()->getHelpersByName();
  }
  /**
   * Is a particular helper loaded in the broker&#63;
   *
   * @param string $name
   * @return boolean
   */
  public static function hasHelper($name)
  {
    $name = self::_normalizeHelperName($name);
    return isset(self::getStack()->{$name});
  }
  /**
   * Remove a particular helper from the broker
   *
   * @param string $name
   * @return boolean
   */
  public static function removeHelper($name)
  {
    $name = self::_normalizeHelperName($name);
    $stack = self::getStack();
    if (isset($stack->{$name})) {
      unset($stack->{$name});
    }
    return false;
  }
  /**
   * Lazy load the priority stack and return it
   *
   * @return Zend_Controller_Action_HelperBroker_PriorityStack
   */
  public static function getStack()
  {
    if (self::$_stack == null) {
      self::$_stack = new Zend_Controller_Action_HelperBroker_PriorityStack();
    }
    return self::$_stack;
  }
  /**
   * Constructor
   *
   * @param Zend_Controller_Action $actionController
   * @return void
   */
  public function __construct(Zend_Controller_Action $actionController)
  {
    $this->_actionController = $actionController;
    foreach (self::getStack() as $helper) {
      $helper->setActionController($actionController);
      $helper->init();
    }
  }
  /**
   * notifyPreDispatch() - called by action controller dispatch method
   *
   * @return void
   */
  public function notifyPreDispatch()
  {
    foreach (self::getStack() as $helper) {
      $helper->preDispatch();
    }
  }
  /**
   * notifyPostDispatch() - called by action controller dispatch method
   *
   * @return void
   */
  public function notifyPostDispatch()
  {
    foreach (self::getStack() as $helper) {
      $helper->postDispatch();
    }
  }
  /**
   * getHelper() - get helper by name
   *
   * @param string $name
   * @return Zend_Controller_Action_Helper_Abstract
   */
  public function getHelper($name)
  {
    $name = self::_normalizeHelperName($name);
    $stack = self::getStack();
    if (!isset($stack->{$name})) {
      self::_loadHelper($name);
    }
    $helper = $stack->{$name};
    $initialize = false;
    if (null === ($actionController = $helper->getActionController())) {
      $initialize = true;
    } elseif ($actionController !== $this->_actionController) {
      $initialize = true;
    }
    if ($initialize) {
      $helper->setActionController($this->_actionController)
          ->init();
    }
    return $helper;
  }
  /**
   * Method overloading
   *
   * @param string $method
   * @param array $args
   * @return mixed
   * @throws Zend_Controller_Action_Exception if helper does not have a direct() method
   */
  public function __call($method, $args)
  {
    $helper = $this->getHelper($method);
    if (!method_exists($helper, 'direct')) {
      require_once 'Zend/Controller/Action/Exception.php';
      throw new Zend_Controller_Action_Exception('Helper "' . $method . '" does not support overloading via direct()');
    }
    return call_user_func_array(array($helper, 'direct'), $args);
  }
  /**
   * Retrieve helper by name as object property
   *
   * @param string $name
   * @return Zend_Controller_Action_Helper_Abstract
   */
  public function __get($name)
  {
    return $this->getHelper($name);
  }
  /**
   * Normalize helper name for lookups
   *
   * @param string $name
   * @return string
   */
  protected static function _normalizeHelperName($name)
  {
    if (strpos($name, '_') !== false) {
      $name = str_replace(' ', '', ucwords(str_replace('_', ' ', $name)));
    }
    return ucfirst($name);
  }
  /**
   * Load a helper
   *
   * @param string $name
   * @return void
   */
  protected static function _loadHelper($name)
  {
    try {
      $class = self::getPluginLoader()->load($name);
    } catch (Zend_Loader_PluginLoader_Exception $e) {
      require_once 'Zend/Controller/Action/Exception.php';
      throw new Zend_Controller_Action_Exception('Action Helper by name ' . $name . ' not found', 0, $e);
    }
    $helper = new $class();
    if (!$helper instanceof Zend_Controller_Action_Helper_Abstract) {
      require_once 'Zend/Controller/Action/Exception.php';
      throw new Zend_Controller_Action_Exception('Helper name ' . $name . ' -> class ' . $class . ' is not of type Zend_Controller_Action_Helper_Abstract');
    }
    self::getStack()->push($helper);
  }
}

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Common usage of assistant broker:

1. Register an assistant

Zend_Controller_Action_HelperBroker::addHelper($helper);

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2. Use the addPrefix() method with a class prefix parameter to add the path to the custom helper class.
The prefix is required to follow Zend Framework's class naming convention.

// Add helpers prefixed with My_Action_Helpers in My/Action/Helpers/
Zend_Controller_Action_HelperBroker::addPrefix('My_Action_Helpers');

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3. Use the addPath() method. The first parameter is a directory, and the second parameter is the class prefix (default is 'Zend_Controller_Action_Helper').

is used to map your own class prefix to the specified directory.

// Add helpers prefixed with Helper in Plugins/Helpers/
Zend_Controller_Action_HelperBroker::addPath('./Plugins/Helpers',
                       'Helper');

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2. Whether the Interpretation Assistant exists

Use the hasHelper($name) method to determine whether an assistant exists in the assistant broker. $name is the short name of the assistant (with the prefix removed):

// Check if 'redirector' helper is registered with the broker:
if (Zend_Controller_Action_HelperBroker::hasHelper('redirector')) {
  echo 'Redirector helper registered';
}

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There are two static methods to get the helper from the helper broker: getExistingHelper() and getStaticHelper() . getExistingHelper() will get the helper only if it has been called before or explicitly registered with the helper broker, otherwise it will throw an exception. getStaticHelper() does the same as getExistingHelper(), but if the helper stack has not been registered, it will try to initialize the helper. To get the helper you want to configure, getStaticHelper() is a good choice.

Both methods take one parameter, $name, which is the short name of the helper (with the prefix removed).

// Check if 'redirector' helper is registered with the broker, and fetch:
if (Zend_Controller_Action_HelperBroker::hasHelper('redirector')) {
  $redirector =
    Zend_Controller_Action_HelperBroker::getExistingHelper('redirector');
}
// Or, simply retrieve it, not worrying about whether or not it was
// previously registered:
$redirector =
  Zend_Controller_Action_HelperBroker::getStaticHelper('redirector');
}

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3. removeHelper($name) deletes an assistant in the assistant broker, $name is the short name of the assistant .

// Conditionally remove the 'redirector' helper from the broker:
if (Zend_Controller_Action_HelperBroker::hasHelper('redirector')) {
  Zend_Controller_Action_HelperBroker::removeHelper('redirector')
}

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