Actions

J3.x

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

From Joomla! Documentation

< J3.x:Developing a MVC Component
Revision as of 16:47, 20 January 2014 by Onliner (Talk | contribs)


Introduction

This tutorial is part of the Developing a Model-View-Controller (MVC) Component for Joomla! 3.x tutorial. You are encouraged to read the previous parts of the tutorial before reading this.

In the Joomla!3.x framework, third party component 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: JControllerLegacy. 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 = JControllerLegacy::getInstance('HelloWorld');
 
// Perform the Request task
$input = JFactory::getApplication()->input;
$controller->execute($input->getCmd('task'));
 
// Redirect if set by the controller
$controller->redirect();

The getInstance static method of the JControllerLegacy class will create a controller. In the code above, it will instantiate a controller object of a class named HelloWorldController. Joomla will look for the declaration of that class in an aptly named file called controller.php (it's a default behavior).

Now, controller.php needs to be created and HelloWorldController needs to be declared and defined. So with your favorite file manager and editor, create a site/controller.php file containing

site/controller.php

<?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 JControllerLegacy
{
}

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

So with task simply a public function display() of JControllerLegacy is refered to.


Tip-icon.png
A Tip!

Just a side note for completion, you could call another function aside from display() by using an URL like this one:

http://localhost/index.php?option=com_helloworld&task=insert
This would try to call a function insert() of our controller (which we would actually have to implement in HelloWorldController ).

Setting the view

When JControllerLegacy wants to display a view, it will look for certain files in the component/com_[component_name]/views/[name of view]/ folder.

The name of the folder of the default view is the name of the component itself. In our case the path is component/com_helloworld/views/helloworld/.

The file that will contain the code of the view is called view.[view_mode].php. The default view mode, and probably the only view a component might need is the html mode. So this give us our file name which is view.html.php.

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 JViewLegacy
{
        // 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 JViewLegacy class is called with the display task of the JControllerLegacy 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>

This template file will be included by the JViewLegacy class. Therefore, here, $this refers to the HelloWorldViewHelloWorld class.


So to give an example, one could call the view inside the component/com_[component_name]/views/[name of view]/    folder by calling:

http://localhost/joomla/index.php?option=com_helloworld

(this would default to the component/com_helloworld/views/helloworld/ folder) or we could explicitly call the folder by calling

http://localhost/joomla/index.php?option=com_helloworld&view=helloworld

if we change &view=helloworld to something else, e.g. &view=fluffy we would have to create a folder:

component/com_helloworld/views/fluffy/

Copy the contents of views/helloworld to views/fluffy

The classname of the file view.html.php of the fluffy folder would be HelloWorldViewFluffy. Afterwards you can customize the contents of default.php of the fluffy subfolder for custom output and see the output by calling:

http://localhost/joomla/index.php?option=com_helloworld&view=fluffy

Packaging the component

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 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="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>0.0.2</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>
        </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>

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


Tutorial Navigation

Contributors