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Difference between revisions of "Developing a MVC Component/Basic backend"

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* @return void
 
* @return void
 
*/
 
*/
function display($cachable = false)  
+
function display($cachable = false, $urlparams = false)  
 
{
 
{
 
// set default view if not set
 
// set default view if not set
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</source>
 
</source>
 
</span>
 
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''COM_HELLOWORLD_HELLOWORLD_HEADING_ID'' and ''COM_HELLOWORLD_HELLOWORLD_HEADING_GREETING'' are placeholders which will later be replaced with language-specific text. The [http://api.joomla.org/Joomla-Platform/Language/JText.html JText::_] method translates a string into the current language.
  
 
''checkAll'' is a javascript function defined in the Joomla core able to check all items.
 
''checkAll'' is a javascript function defined in the Joomla core able to check all items.

Latest revision as of 16:18, 26 April 2022

This page has been archived. This page contains information for an unsupported Joomla! version or is no longer relevant. It exists only as a historical reference, it will not be improved and its content may be incomplete and/or contain broken links.


Introduction[edit]

This tutorial is part of the Developing a Model-View-Controller (MVC) Component for Joomla!2.5 tutorial. You are encouraged to read the previous parts of the tutorial before reading this.

And check the "discussion" tab for some clarifications.

Basic backend[edit]

Designing the backend interface leads us to create at least a Model-View-Controller triptych. We have to modify 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');

// Get the task
$jinput = JFactory::getApplication()->input;
$task = $jinput->get('task', "", 'STR' );
 
// Perform the Request task
$controller->execute($task);
 
// Redirect if set by the controller
$controller->redirect();

Create the general controller[edit]

The entry point now gets an instance of a HelloWorld prefixed controller. Let's 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, $urlparams = false) 
	{
		// set default view if not set
		$input = JFactory::getApplication()->input;
		$input->set('view', $input->getCmd('view', 'HelloWorlds'));
 
		// call parent behavior
		parent::display($cachable);
	}
}

This controller will display the 'HelloWorlds' view by default.

Create the view[edit]

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

admin/views/helloworlds/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');

/**
 * HelloWorlds View
 */
class HelloWorldViewHelloWorlds extends JView
{
	/**
	 * HelloWorlds view display method
	 * @return void
	 */
	function display($tpl = null) 
	{
		// Get data from the model
		$items = $this->get('Items');
		$pagination = $this->get('Pagination');

		// Check for errors.
		if (count($errors = $this->get('Errors'))) 
		{
			JError::raiseError(500, implode('<br />', $errors));
			return false;
		}
		// 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/helloworlds/tmpl/default.php containing

admin/views/helloworlds/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/helloworlds/tmpl/default_head.php containing

admin/views/helloworlds/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_HEADING_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_HEADING_GREETING'); ?>
	</th>
</tr>


COM_HELLOWORLD_HELLOWORLD_HEADING_ID and COM_HELLOWORLD_HELLOWORLD_HEADING_GREETING are placeholders which will later be replaced with language-specific text. The JText::_ method translates a string into the current language.

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

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

admin/views/helloworlds/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 a helper function able to display several HTML output. In this case, it will display a checkbox for the item.

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

admin/views/helloworlds/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 HelloWorlds view asks the model for data. In Joomla, there is a class able to manage a list of data: JModelList. Class JModelList and inherited classes need only one method:

  • getListQuery which constructs an SQL query

and two states:

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

The getItems and getPagination methods are defined in JModelList class. They don't need to be defined in the HelloWorldModelHelloWorlds class.

admin/models/helloworlds.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 HelloWorldModelHelloWorlds extends JModelList
{
	/**
	 * Method to build an SQL query to load the list data.
	 *
	 * @return	string	An SQL query
	 */
	protected function getListQuery()
	{
		// Create a new query object.		
		$db = JFactory::getDBO();
		$query = $db->getQuery(true);
		// Select some fields
		$query->select('id,greeting');
		// From the hello table
		$query->from('#__helloworld');
		return $query;
	}
}

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. 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="2.5.0" 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; New in 2.5 -->
		<schemas>
			<schemapath type="mysql">sql/updates/mysql</schemapath>
		</schemas>
	</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>

Now you can see in your component hello-world an array with two colums, two rows and checkboxes. You can click the checkboxes in order to select the different options you want.

Navigate[edit]

Prev: Using the database Next: Adding language management

Contributors[edit]