Joomla components and execution path

The entry point into a Joomla! component is similar fromcomponent to component. <wbr>For this example, we willuse the Web Links core component. <wbr>The first fileto be executed in the front end is:</wbr></wbr>

.../components/com_weblinks/weblinks.php

<wbr></wbr>

First we see the security check to make sure no one calls thispage directly. <wbr>This is standard and should be inall your php files (although there are a few exceptions):</wbr>

// no direct access

defined('_JEXEC') or die('Restricted access');

<wbr></wbr>

Next, we require (include) the controller.php class that is inthe same directory:

// Require the base controller

require_once (JPATH_COMPONENT.DS.'controller.php');

<wbr></wbr>

We check the query string to see if a specific controller namewas sent in. <wbr>If so, we make sure to require therequired file in the controllers directory as well:</wbr>

<wbr></wbr>

// Require specific controller if requested

if($controller = JRequest::getWord('controller')) {

       $path = JPATH_COMPONENT.DS.'controllers'.DS.$controller.'.php';

       if (file_exists($path)) {

             require_once $path;

   } else {

              $controller = '';

     }

}

<wbr></wbr>

<wbr></wbr>

We then create an instance of our controller using the name weset above:

// Create the controller

$classname = 'WeblinksController'.ucfirst($controller);

$controller = new $classname( );

<wbr></wbr>

And execute the task that was requested in the query stringparameter:

// Perform the Request task

$controller->execute(JRequest::getCmd('task'));

<wbr></wbr>

Once the task is complete, we redirect if needed:

// Redirect if set by the controller

$controller->redirect();

<wbr></wbr>

Next, we open up the controller class.

The generic controller for the Web Links component can be foundhere:

.../components/com_weblinks/controller.php

All this class defines is the display method, which is thedefault used if the user does not specify a task.

<wbr></wbr>

<?php


// Check to ensure this file is included in Joomla!
defined('_JEXEC') or die( 'Restricted access' );

jimport('joomla.application.component.controller');


class WeblinksController extends JController
{
        
        function display()
        {
                // Set a default view if none exists
                if ( ! JRequest::getCmd( 'view' ) ) {
                        JRequest::setVar('view', 'categories' );
                }

                //update the hit count for the weblink
                if(JRequest::getCmd('view') == 'weblink')
                {
                        $model =& $this->getModel('weblink');
                        $model->hit();
                }
                
                // View caching logic -- simple... are we logged in?
                $user = &JFactory::getUser();
                $view = JRequest::getVar('view');
                $viewcache = JRequest::getVar('viewcache', '1', 'POST', 'INT');
                if ($user->get('id') || ($view == 'category' && $viewcache == 0)) {
                        parent::display(false);
                } else {
                        parent::display(true);
                }
        }
}

<wbr></wbr>

<wbr></wbr>

In this method, we set the default view to be categories if onewas not passed in as a query string parameter. <wbr>Ifthe requested view is a weblink, we make sure to increment thecounter. <wbr>We then setup the view variable and callthe diplay method on our parent class (JController).</wbr></wbr>

<wbr></wbr>

One thing to notice here is the getModel call.<wbr>This will go out and load up the required modelfor the component. <wbr>In this case, it will load theweblink model found here:</wbr></wbr>

.../components/com_weblinks/models/weblink.php

<wbr></wbr>

At this point, we will assume no view was passed in andtherefore our view will be set to "categories".

<wbr></wbr>

Next, we open up the view class.

Since we are assuming we want the categories view, this is thenext file to be executed:

.../components/com_weblinks/views/categories/view.html.php

<?php


// Check to ensure this file is included in Joomla!
defined( '_JEXEC' ) or die( 'Restricted access' );

jimport( 'joomla.application.component.view');


class WeblinksViewCategories extends JView
{
        function display( $tpl = null)
        {
                global $mainframe;

                $document =& JFactory::getDocument();

                $categories     =& $this->get('data');
                $total          =& $this->get('total');
                $state          =& $this->get('state');

                // Get the page/component configuration
                $params = &$mainframe->getParams();

                $menus  = &JSite::getMenu();
                $menu   = $menus->getActive();

                // because the application sets a default page title, we need to get it
                // right from the menu item itself
                if (is_object( $menu )) {
                        $menu_params = new JParameter( $menu->params );
                        if (!$menu_params->get( 'page_title')) {
                                $params->set('page_title',       JText::_( 'Web Links' ));
                        }
                } else {
                        $params->set('page_title',       JText::_( 'Web Links' ));
                }

                $document->setTitle( $params->get( 'page_title' ) );

                // Set some defaults if not set for params
                $params->def('comp_description', JText::_('WEBLINKS_DESC'));

                // Define image tag attributes
                if ($params->get('image') != -1)
                {
                        if($params->get('image_align')!="")
                                $attribs['align'] = $params->get('image_align');
                        else
                                $attribs['align'] = '';
                        $attribs['hspace'] = 6;

                        // Use the static HTML library to build the image tag
                        $image = JHTML::_('image', 'images/stories/'.$params->get('image'), JText::_('Web Links'), $attribs);
                }

                for($i = 0; $i < count($categories); $i++)
                {
                        $category =& $categories[$i];
                        $category->link = JRoute::_('index.php?option=com_weblinks&view=category&id='. $category->slug);

                        // Prepare category description
                        $category->description = JHTML::_('content.prepare', $category->description);
                }

                $this->assignRef('image',                $image);
                $this->assignRef('params',               $params);
                $this->assignRef('categories',   $categories);

                parent::display($tpl);
        }
}
?>

<wbr></wbr>

Again, it is a very simple class with one display method.<wbr>A lot of the logic here is specific to the WebLinks component, but you will start to see similar functionalitybeing used across a lot of component view classes.<wbr>At the end of the display method, this class willcall the parent (JView) display method passing in the template nameto display. <wbr>If no name is passed in, the"default" template is used.</wbr></wbr></wbr>

<wbr></wbr>

And last, we open up the template class.

We will assume that no template name was passed in and thereforethe default template is being used. <wbr>In this case,the next file to look at is this one:</wbr>

.../components/com_weblinks/views/categories/tmpl/default.php

<?php // no direct access
defined('_JEXEC') or die('Restricted access'); ?>
<?php if ( $this->params->def( 'show_page_title', 1 ) ) : ?>
        <div class="componentheading">
                <?php echo $this->escape($this->params->get('page_title')); ?>
        </div>
<?php endif; ?>

<?php if ( ($this->params->def('image', -1) != -1) || $this->params->def('show_comp_description', 1) ) : ?>
<table width="100%" cellpadding="4" cellspacing="0" border="0" align="center" class="contentpane">
<tr>
        <td valign="top" class="contentdescription">
        <?php
                if ( isset($this->image) ) :  echo $this->image; endif;
                echo $this->params->get('comp_description');
        ?>
        </td>
</tr>
</table>
<?php endif; ?>
<ul>
<?php foreach ( $this->categories as $category ) : ?>
        <li>
                <a href="/" class="category">
                        <?php echo $this->escape($category->title);?></a>
                &nbsp;
                <span class="small">
                        (<?php echo $category->numlinks;?>)
                </span>
        </li>
<?php endforeach; ?>
</ul>

Most of the logic here will be very specific to the component being executed.

A few of the other file types you might find incomponents:

• Helpers - There may be a helper.php file or a helpers directorywith many files. <wbr>These files typically just storecommon functionality for the component.</wbr>
• Assets - This seems to be a catch-all folder for other thingsto include in a component.
• router.php - This file is used when SEF urls are turned on totranslate URLs in both directions.
• xml files - These typically define parameters and otherinformation about the component and it's views.<wbr>These are used when creating menu items for acomponent.</wbr>
• index.html - It's good practice to have a blank index.html filein all your directories. <wbr>This is another securitymeasure.</wbr>
• css/images/js - Folders that contain different files forstyling and client side functionality