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Developing a MVC Component/Adding language management

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Articles in this series[edit]

Indroduction[edit]

This tutorial is part of the Developing a Model-View-Controller (MVC) Component for Joomla!1.6 tutorial. You are encouraged to read the previous parts of the tutorial before reading this.

Basic backend[edit]

Designing the backend interface leads us to create at least a Model-View-Controller triptych. We have to modified the administrator entry point of our component, the admin/helloworld.php file

admin/helloworld.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
// import joomla controller library
jimport('joomla.application.component.controller');
// Get an instance of the controller prefixed by HelloWorld
$controller = JController::getInstance('HelloWorld');
// Perform the Request task
$controller->execute(JRequest::getCmd('task'));
// Redirect if set by the controller
$controller->redirect();

Create the general controller[edit]

The entry point now get an instance of a HelloWorld prefixed controller. Let create a basic controller for the administrator part:

admin/controller.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
// import Joomla controller library
jimport('joomla.application.component.controller');
/**
 * General Controller of HelloWorld component
 */
class HelloWorldController extends JController
{
	/**
	 * display task
	 *
	 * @return void
	 */
	function display($cachable = false) 
	{
		// set default view if not set
		JRequest::setVar('view', JRequest::getCmd('view', 'HelloWorldList'));
		// call parent behavior
		parent::display($cachable);
	}
}

This controller will display the 'HelloWorldList view by default.

Create the view[edit]

With your favorite file manager and editor, create a file admin/views/helloworldlist/view.html.php containing:

admin/views/helloworldlist/view.html.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
// import Joomla view library
jimport('joomla.application.component.view');
/**
 * HelloWorldList View
 */
class HelloWorldViewHelloWorldList extends JView {
	/**
	 * items to be displayed
	 */
	protected $items;
	/**
	 * pagination for the items
	 */
	protected $pagination;
	/**
	 * HelloWorldList view display method
	 * @return void
	 */
	function display($tpl = null)
	{
		// Get data from the model
		$items = $this->get('Items');
		$pagination = $this->get('Pagination');
		// Assign data to the view
		$this->items = $items;
		$this->pagination = $pagination;
		// Display the template
		parent::display($tpl);
	}
}

In Joomla, views display data using layout. With your favorite file manager and editor, put a file admin/views/helloworldlist/tmpl/default.php containing

admin/views/helloworldlist/tmpl/default.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted Access');
// load tooltip behavior
JHtml::_('behavior.tooltip');
?>
<form action="<?php echo JRoute::_('index.php?option=com_helloworld'); ?>" method="post" name="adminForm">
	<table class="adminlist">
		<thead><?php echo $this->loadTemplate('head');?></thead>
		<tfoot><?php echo $this->loadTemplate('foot');?></tfoot>
		<tbody><?php echo $this->loadTemplate('body');?></tbody>
	</table>
</form>

This layout calls several sub-layout (head, foot and body). Each sub-layout corresponds to a file prefixed by the name of the main layout (default), and an underscore.

Put a file admin/views/helloworldlist/tmpl/default_head.php containing

admin/views/helloworldlist/tmpl/default_head.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted Access');
?>
<tr>
	<th width="5">
		<?php echo JText::_('com_helloworld_HELLOWORLD_ID'); ?>
	</th>
	<th width="20">
		<input type="checkbox" name="toggle" value="" onclick="checkAll(<?php echo count($this->items); ?>);" />
	</th>			
	<th>
		<?php echo JText::_('com_helloworld_HELLOWORLD_GREETING'); ?>
	</th>
</tr>

checkAll is a javascript function defined in the Joomla core able to check all items.

Put a file admin/views/helloworldlist/tmpl/default_body.php containing

admin/views/helloworldlist/tmpl/default_body.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted Access');
?>
<?php foreach($this->items as $i => $item): ?>
	<tr class="row<?php echo $i % 2; ?>">
		<td>
			<?php echo $item->id; ?>
		</td>
		<td>
			<?php echo JHtml::_('grid.id', $i, $item->id); ?>
		</td>
		<td>
			<?php echo $item->greeting; ?>
		</td>
	</tr>
<?php endforeach; ?>

JHtml::_ is an helper function able to display several HTML output. In this case, it will display a checkbox for the item.

Put a file admin/views/helloworldlist/tmpl/default_foot.php containing

admin/views/helloworldlist/tmpl/default_foot.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted Access');
?>
<tr>
	<td colspan="3"><?php echo $this->pagination->getListFooter(); ?></td>
</tr>

JPagination is a Joomla class able to manage and display pagination object.

Create the model[edit]

The HelloWorldList view asks the model for data. In Joomla!1.6, there is a class able to manage list of data: JModelList. Class JModelList and inherited classes needs only one method:

  • _getListQuery which constructs and SQL query

and two states:

  • list.start for determining the list offset
  • list.limit for determining the list length

getItems and getPagination method are defined in JModelList class. They don't need to be defined in the HelloWorldModelHelloWorldList class.

admin/models/helloworldlist.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
// import the Joomla modellist library
jimport('joomla.application.component.modellist');
/**
 * HelloWorldList Model
 */
class HelloWorldModelHelloWorldList extends JModelList {
	/**
	 * Model context string.
	 *
	 * @var		string
	 */
	protected $_context = 'com_helloworld.helloworldlist';
	/**
	 * Method to build an SQL query to load the list data.
	 *
	 * @return	string	An SQL query
	 */
	protected function _getListQuery() {
		// Create a new query object.
		$query = new JQuery;
		// Select some fields
		$query->select('id,greeting');
		// From the hello table
		$query->from('#__helloworld');
		return $query;
	}
	/**
	 * Method to auto-populate the model state.
	 *
	 * This method should only be called once per instantiation and is designed
	 * to be called on the first call to the getState() method unless the model
	 * configuration flag to ignore the request is set.
	 *
	 * @return	void
	 */
	protected function _populateState() {
		// Initialize variables.
		$app = JFactory::getApplication('administrator');
		// Load the list state.
		$this->setState('list.start', $app->getUserStateFromRequest($this->_context . '.list.start', 'limitstart', 0, 'int'));
		$this->setState('list.limit', $app->getUserStateFromRequest($this->_context . '.list.limit', 'limit', $app->getCfg('list_limit', 25), 'int'));
	}
}

The _populateState method is, by default, automatically called when a state is read by the getState method.

Packaging the component[edit]

Content of your code directory

Create a compressed file of this directory or directly download the archive and install it using the extension manager of Joomla!1.6. You can add a menu item of this component using the menu manager in the backend.

helloworld.xml

<?xml version="1.0" encoding="utf-8"?>
<extension type="component" version="1.6.0" method="upgrade">
	<name>Hello World!</name>
	<creationDate>November 2009</creationDate>
	<author>John Doe</author>
	<authorEmail>john.doe@example.org</authorEmail>
	<authorUrl>http://www.example.org</authorUrl>
	<copyright>Copyright Info</copyright>
	<license>License Info</license>
	<version>0.0.7</version>
	<description>Description of the Hello World component ...</description>

	<install> <!-- Runs on install -->
		<sql>
			<file driver="mysql" charset="utf8">sql/install.mysql.utf8.sql</file>
		</sql>
	</install>
	<uninstall> <!-- Runs on uninstall -->
		<sql>
			<file driver="mysql" charset="utf8">sql/uninstall.mysql.utf8.sql</file>
		</sql>
	</uninstall>
	<update> <!-- Runs on update -->
		<sql>
			<file driver="mysql" charset="utf8">sql/update.mysql.utf8.sql</file>
		</sql>
	</update>

	<files folder="site">
		<filename>index.html</filename>
		<filename>helloworld.php</filename>
		<filename>controller.php</filename>
		<folder>views</folder>
		<folder>models</folder>
	</files>

	<administration>
		<menu>Hello World!</menu>
		<files folder="admin">
			<filename>index.html</filename>
			<filename>helloworld.php</filename>
			<filename>controller.php</filename>
			<folder>sql</folder>
			<folder>tables</folder>
			<folder>models</folder>
			<!-- views files section -->
			<folder>views</folder>
		</files>		
	</administration>
</extension>

Contributors[edit]