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Developing a MVC Component/Adding a model to the site part

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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.

Adding a model[edit]

In the Joomla framework, models are responsible for managing the data. The first function that has to be written for a model is a get function. It returns data to the caller. In our case, the caller will be the HelloWorldViewHelloWorld view. By default, the model named HelloWorldModelHelloWorld is the main model associated to this view. with your favorite file manager and editor put a site/models/helloworld.php file containing:

site/models/helloworld.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');

// import Joomla modelitem library
jimport('joomla.application.component.modelitem');

/**
 * HelloWorld Model
 */
class HelloWorldModelHelloWorld extends JModelItem
{
	/**
	 * @var string msg
	 */
	protected $msg;

	/**
	 * Get the message
	 * @return string The message to be displayed to the user
	 */
	public function getMsg() 
	{
		if (!isset($this->msg)) 
		{
			$this->msg = 'Hello World!';
		}
		return $this->msg;
	}
}

The HelloWorldViewHelloWorld class asks the model for data using the get method of the JView class:

site/views/helloworld/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');

/**
 * HTML View class for the HelloWorld Component
 */
class HelloWorldViewHelloWorld extends JView
{
	// Overwriting JView display method
	function display($tpl = null) 
	{
		// Assign data to the view
		$this->msg = $this->get('Msg');

		// Check for errors.
		if (count($errors = $this->get('Errors'))) 
		{
			JLog::add(implode('<br />', $errors), JLog::WARNING, 'jerror');
			return false;
		}
		// Display the view
		parent::display($tpl);
	}
}

Note: $this->get() is a member of JView::get which is a proxy to get* methods of the default model where * is populated with the value of the first parameter passed to get()

Also modify your helloworld.xml file to indicate use of models and the new version:

helloworld.xml

<?xml version="1.0" encoding="utf-8"?>
<extension type="component" version="2.5.0" method="upgrade">

	<name>Hello World!</name>
	<!-- The following elements are optional and free of formatting constraints -->
	<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>
	<!--  The version string is recorded in the components table -->
	<version>0.0.4</version>
	<!-- The description is optional and defaults to the name -->
	<description>Description of the Hello World component ...</description>

	<update> <!-- Runs on update; New in 2.5 -->
		<schemas>
			<schemapath type="mysql">sql/updates/mysql</schemapath>
		</schemas>
	</update>

	<!-- Site Main File Copy Section -->
	<!-- Note the folder attribute: This attribute describes the folder
		to copy FROM in the package to install therefore files copied
		in this section are copied from /site/ in the package -->
	<files folder="site">
		<filename>index.html</filename>
		<filename>helloworld.php</filename>
		<filename>controller.php</filename>
		<folder>views</folder>
		<folder>models</folder>
	</files>

	<administration>
		<!-- Administration Menu Section -->
		<menu>Hello World!</menu>
		<!-- Administration Main File Copy Section -->
		<!-- Note the folder attribute: This attribute describes the folder
			to copy FROM in the package to install therefore files copied
			in this section are copied from /admin/ in the package -->
		<files folder="admin">
			<!-- Admin Main File Copy Section -->
			<filename>index.html</filename>
			<filename>helloworld.php</filename>
			<!-- SQL files section -->
			<folder>sql</folder>
		</files>
	</administration>

</extension>

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.

Navigate[edit]

Prev: Adding a menu type to the site part Next: Adding a variable request in the menu type

Contributors[edit]