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J2.5

Developing a MVC Component/Adding an install-uninstall-update script file

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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.


Creating the extension script file

Installing, updating and uninstalling a component may require additional operations that cannot be achieved by the basic operations described in the main xml file. Joomla 1.6 offers a new approach to solve this problem. It consists in using a php script file containing a class using five methods:

  • preflight which is executed before install and update
  • install
  • update
  • uninstall
  • postflight which is executed after install and update

Writing an extension script consists in declaring an class whose name is com_ComponentNameInstallerScript with these 5 methods.

script.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
 
/**
 * Script file of HelloWorld component
 */
class com_helloWorldInstallerScript
{
        /**
         * method to install the component
         *
         * @return void
         */
        function install($parent) 
        {
                // $parent is the class calling this method
                $parent->getParent()->setRedirectURL('index.php?option=com_helloworld');
        }
 
        /**
         * method to uninstall the component
         *
         * @return void
         */
        function uninstall($parent) 
        {
                // $parent is the class calling this method
                echo '<p>' . JText::_('COM_HELLOWORLD_UNINSTALL_TEXT') . '</p>';
        }
 
        /**
         * method to update the component
         *
         * @return void
         */
        function update($parent) 
        {
                // $parent is the class calling this method
                echo '<p>' . JText::_('COM_HELLOWORLD_UPDATE_TEXT') . '</p>';
        }
 
        /**
         * method to run before an install/update/uninstall method
         *
         * @return void
         */
        function preflight($type, $parent) 
        {
                // $parent is the class calling this method
                // $type is the type of change (install, update or discover_install)
                echo '<p>' . JText::_('COM_HELLOWORLD_PREFLIGHT_' . $type . '_TEXT') . '</p>';
        }
 
        /**
         * method to run after an install/update/uninstall method
         *
         * @return void
         */
        function postflight($type, $parent) 
        {
                // $parent is the class calling this method
                // $type is the type of change (install, update or discover_install)
                echo '<p>' . JText::_('COM_HELLOWORLD_POSTFLIGHT_' . $type . '_TEXT') . '</p>';
        }
}

This script file will redirect the user to the com_helloworld component when it is installed and will display messages when it is updated or uninstalled.

Adding some language keys

admin/language/en-GB/en-GB.com_helloworld.sys.ini""

COM_HELLOWORLD="Hello World!"
COM_HELLOWORLD_DESCRIPTION="This is the Hello World description"
COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_DESC="This view displays a selected message"
COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_TITLE="Hello World"
COM_HELLOWORLD_INSTALL_TEXT="HelloWorld Install script"
COM_HELLOWORLD_MENU="Hello World!"
COM_HELLOWORLD_POSTFLIGHT_DISCOVER_INSTALL_TEXT="HelloWorld postlight discover install script"
COM_HELLOWORLD_POSTFLIGHT_INSTALL_TEXT="HelloWorld postflight install script"
COM_HELLOWORLD_POSTFLIGHT_UNINSTALL_TEXT="HelloWorld postflight uninstall script"
COM_HELLOWORLD_POSTFLIGHT_UPDATE_TEXT="HelloWorld postflight update script"
COM_HELLOWORLD_PREFLIGHT_DISCOVER_INSTALL_TEXT="HelloWorld preflight discover install script"
COM_HELLOWORLD_PREFLIGHT_INSTALL_TEXT="HelloWorld preflight install script"
COM_HELLOWORLD_PREFLIGHT_UNINSTALL_TEXT="HelloWorld preflight uninstall script"
COM_HELLOWORLD_PREFLIGHT_UPDATE_TEXT="HelloWorld preflight update script"
COM_HELLOWORLD_UNINSTALL_TEXT="HelloWorld Uninstall script"
COM_HELLOWORLD_UPDATE_TEXT="HelloWorld Update script"

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!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>COM_HELLOWORLD</name>
        <!-- The following elements are optional and free of formatting conttraints -->
        <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>0.0.15</version>
        <!-- The description is optional and defaults to the name -->
        <description>COM_HELLOWORLD_DESCRIPTION</description>
 
        <!-- Runs on install/uninstall/update; New in 1.6 -->
        <scriptfile>script.php</scriptfile>
 
        <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 1.6 -->
                <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>
                <folder>language</folder>
        </files>
 
        <media destination="com_helloworld" folder="media">
                <filename>index.html</filename>
                <folder>images</folder>
        </media>
 
        <administration>
                <!-- Administration Menu Section -->
                <menu img="../media/com_helloworld/images/tux-16x16.png">COM_HELLOWORLD_MENU</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>config.xml</filename>
                        <filename>access.xml</filename>
                        <filename>script.php</filename>
                        <filename>helloworld.php</filename>
                        <filename>controller.php</filename>
                        <!-- SQL files section -->
                        <folder>sql</folder>
                        <!-- tables files section -->
                        <folder>tables</folder>
                        <!-- models files section -->
                        <folder>models</folder>
                        <!-- views files section -->
                        <folder>views</folder>
                        <!-- controllers files section -->
                        <folder>controllers</folder>
                        <!-- helpers files section -->
                        <folder>helpers</folder>
                </files>
 
                <languages folder="admin">
                        <language tag="en-GB">language/en-GB/en-GB.com_helloworld.ini</language>
                        <language tag="en-GB">language/en-GB/en-GB.com_helloworld.sys.ini</language>
                </languages>
        </administration>
 
</extension>

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