ZendFramework action assistant (Zend_Controller_Action_Helper)

This article mainly introduces the ZendFramework action assistant (Zend_Controller_Action_Helper) usage, detailed analysis of the action assistant Zend_Controller_Action_Helper function, definition, usage and related implementation code, for more information about Zend Framework action assistant (Zend_Controller_Action_Helper), see the following example. We will share this with you for your reference. The details are as follows:

Through the assistant mode, some frequently used functional modules can be encapsulated to be flexibly used as needed, mainly in action.

Zend Framework has two assistants: Action assistant (Zend_Controller_Action_Helper) and attempt assistant (Zend_View_Helper ).

The action assistant can instantly add features (runtime and/or on-demand functionality) to any Zend_Controller_Action derivative action controller, so that when the public action controller function is added, minimize the need for derivative action controller classes.

The action assistant is loaded when it needs to be called. it can be instantiated at the time of request (bootstrap) or when the action controller is created (init.

Related files 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::

Flash Messenger is used to process 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 redirect programs to internal or external pages;
ViewRenderer automatically creates a view object in the controller and renders the view;
AutoComplete automatically responds to AJAX's automatic completion;
ContextSwitch and AjaxContext provide alternative response formats for your actions;
Cache-related operations;
ActionStack is used to operate action stacks.

Several practical examples

1. use the getHelper () method of the $ _ helper member of Zend_Controller_Action. Call getHelper () directly and enter the assistant name.

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

2. directly access the helper object corresponding to the _ helper assistant attribute.

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

Zend_Controller_Action_HelperBroker

The Chinese name is translated as "assistant broker". as the name suggests, it is the intermediary of the action assistant.

The second method used in the action instantiation is implemented through the magic method _ get () of Zend_Controller_Action_HelperBroker.

The assistant broker registers assistant objects and assistant paths, and obtains assistants.

Implementation of Zend_Controller_Action_HelperBroker and List of common methods

<?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?   *   * @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);  }}

Common use of assistant broker:

1. register an assistant

1.

Zend_Controller_Action_HelperBroker::addHelper($helper);

2. the addPrefix () method carries a class prefix parameter to add the path of the custom assistant class.
The prefix is required to follow the class naming conventions of Zend Framework.

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

3. use addPath () method. The first parameter is a directory, and the second parameter is a class prefix ('zend _ Controller_Action_Helper 'by default ').

Used to map the class prefix to the specified directory.

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

II. checking whether 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 (excluding the prefix ):

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

There are two static methods for obtaining the assistant from the assistant broker: getExistingHelper () and getStaticHelper (). GetExistingHelper () will get the assistant only if it has previously called or explicitly registered through the assistant broker, otherwise an exception will be thrown. GetStaticHelper () is the same as getExistingHelper (). However, if you have not registered the assistant stack, it will try to initialize the assistant. to get the assistant you want to configure, getStaticHelper () is a good choice.

Both methods contain a parameter $ name, which is the short name of the Assistant (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');}

3. removeHelper ($ name) deletes an assistant from 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')}