J2.5:Developing a MVC Component/Adding a view to the site part

Revision as of 19:01, 21 November 2010

Template:Future

Articles in this series

Developing a MVC (MVC) Component  Introduction  Developing a Basic Component  Adding a view to the site part  Adding a menu type to the site part  Adding a model to the site part  Adding a variable request in the menu type  Using the database  Basic backend  Adding language management  Adding backend actions  Adding decorations to the backend  Adding verifications  Adding categories  Adding configuration  Adding ACL  Adding an install/uninstall/update script file  Using the language filter facility  Adding an update server  Example of a Frontend Update Function  Example of Menu Parameters & Stylesheets

Introduction

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.

In the Joomla!1.6 framework, third party components authors divide their code into three main parts:

• models They manage the data
• controllers They perform tasks, set and get the states of the models and ask the views to display
• views They display the content according to the type (error, feed, html, json, raw, xml) and the layout chosen by the controllers

Setting the controller

In the core code of Joomla, there is a class able to manage controllers: JController. This class has to be extended to be used in our component. In the file site/helloworld.php (entry point of our Hello World component), put these lines

site/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();

The getInstance static method of the JController class will create a controller. In the code above, it will create a controller named HelloWorldController using the controller.php file (it's a default behavior)

With your favorite file manager and editor, create a site/controller.php file containing

site/controller.php

// No direct access to this file
defined('_JEXEC') or die('Restricted access');
 
// import Joomla controller library
jimport('joomla.application.component.controller');
 
/**
 * Hello World Component Controller
 */
class HelloWorldController extends JController
{
}

When no task is given in the request variables, the default task will be executed. It's the display task by default. The JController class has such a task. In our example, it will display a view named HelloWorld.

Setting the view

With your favorite file manager and editor, create a file site/views/helloworld/view.html.php able to display the default view and containing

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 = 'Hello World';
 
                // Display the view
                parent::display($tpl);
        }
}

The display method of the Jview class is called with the display task of the JController class. In our case, this method will display data using the tmpl/default.php file. With your favorite file manager and editor, create a file site/views/helloworld/tmpl/default.php able to display the default view and containing

site/views/helloworld/tmpl/default.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
?>
<h1><?php echo $this->msg; ?></h1>

Packaging the component

Content of your code directory

• helloworld.xml
• site/index.html
• site/helloworld.php
• site/controller.php
• site/views/index.html
• site/views/helloworld/index.html
• site/views/helloworld/view.html.php
• site/views/helloworld/tmpl/index.html
• site/views/helloworld/tmpl/default.php
• admin/index.html
• admin/helloworld.php

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 test this basic component by putting index.php?option=com_helloworld in your browser address.

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>0.0.2</version>
        <description>Description of the Hello World component ...</description>
 
        <files folder="site">
                <filename>index.html</filename>
                <filename>helloworld.php</filename>
                <!-- The controller is included in the package -->
                <filename>controller.php</filename>
                <!-- The entire views folder is included in the package -->
                <folder>views</folder>
        </files>
 
        <administration>
                <menu>Hello World!</menu>
                <files folder="admin">
                        <filename>index.html</filename>
                        <filename>helloworld.php</filename>
                </files>                
        </administration>
</extension>

Result: You will see by default the message contained in the variable $this->msg in the view.html.php file.

Navigate

Prev: Developing a Basic Component Next: Adding a menu type to the site part

Contributors

• Christophe Demko