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

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This tutorial is for Joomla! CMS Version(s)

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.

Creating the extension script file[edit]

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 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::sprintf('COM_HELLOWORLD_UPDATE_TEXT', $parent->get('manifest')->version) . '</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. In the update method we show the new version using $parent->get('manifest')->version.

Adding some language keys[edit]

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. HelloWorld now updated to version %s."

note: If you want that these languages KEYs to be used at the first install of the component, the sys.ini language file must be stored in the component folder (admin/language/en-GB/en-GB.com_helloworld.sys.ini), and the xml manifest file must contains a folder tag for copying language in the component folder. Modify your Manifest file accordingly:

                <files folder="admin">
                        <!-- language folder -->
                        <folder>language</folder>
                </files>
 
                <languages folder="admin">
                        <language tag="en-GB">language/en-GB/en-GB.com_helloworld.ini</language>
                        <!-- com_helloworld.sys.ini no longer needed there-->
                </languages>

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>COM_HELLOWORLD</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>0.0.15</version>
	<!-- The description is optional and defaults to the name -->
	<description>COM_HELLOWORLD_DESCRIPTION</description>

	<!-- Runs on install/uninstall/update; New in 2.5 -->
	<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 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>
		<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>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>

Navigate[edit]

Prev: Adding ACL Next: Using the language filter facility

Contributors[edit]

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