Joomla! Documentation™

Under Construction

Articles in this serie

• Developing a Basic Component
• Adding a view to the site part
• Adding a menu type to the backend part
• Adding a model to the site part
• Adding a variable request in the menu type
• Using the database

Indroduction

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.

Using the database

Components usually manages their contents using the database. During the install/uninstall/updata phase of a component, you can execute SQL queries through the use of SQL text files.

With your favorite file manager and editor put a file admin/sql/install.mysql.utf8.sql containing:

admin/sql/install.mysql.utf8.sql

DROP TABLE IF EXISTS `#__helloworld`;

CREATE TABLE `#__helloworld` (
  `id` int(11) NOT NULL auto_increment,
  `greeting` varchar(25) NOT NULL,
   PRIMARY KEY  (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;

INSERT INTO `#__helloworld` (`greeting`) VALUES
	('Hello World!'),
	('Good bye World!');

This is the install file. It will be executed if your put an appropriate order in the helloworld.xml file

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>0.0.6</version>
	<description>Description of the Hello World component ...</description>

	<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 -->
		<sql>
			<file driver="mysql" charset="utf8">sql/update.mysql.utf8.sql</file>
		</sql>
	</update>

	<files folder="site">
		<filename>index.html</filename>
		<filename>helloworld.php</filename>
		<filename>controller.php</filename>
		<folder>views</folder>
		<folder>models</folder>
	</files>

	<administration>
		<menu>Hello World!</menu>
		<files folder="admin">
			<filename>index.html</filename>
			<filename>helloworld.php</filename>
			<!-- SQL files section -->
			<folder>sql</folder>
			<!-- tables files section -->
			<folder>tables</folder>
			<!-- models files section -->
			<folder>models</folder>
		</files>		
	</administration>
</extension>

Do the same for the uninstall and update file:

With your favorite file manager and editor put a file admin/sql/uninstall.mysql.utf8.sql containing:

admin/sql/uninstall.mysql.utf8.sql

DROP TABLE IF EXISTS `#__helloworld`;

With your favorite file manager and editor put a file admin/sql/update.mysql.utf8.sql containing:

admin/sql/update.mysql.utf8.sql

DROP TABLE IF EXISTS `#__helloworld`;

CREATE TABLE `#__helloworld` (
  `id` int(11) NOT NULL auto_increment,
  `greeting` varchar(25) NOT NULL,
   PRIMARY KEY  (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;

INSERT INTO `#__helloworld` (`greeting`) VALUES
	('Hello World!'),
	('Good bye World!');

Adding a new field type

For the moment, we have used a hard coded file type for messages. We need to use our database for choosing the message.

Modify the site/views/helloworld/tmpl/default.xml file and put these lines

site/views/helloworld/tmpl/default.xml

<?xml version="1.0" encoding="utf-8"?>

<metadata>

	<layout

		title="com_helloworld_helloworld_view_default_title">

		<message>com_helloworld_helloworld_view_default_desc</message>

	</layout>
	<fields
		group="request"
		array="true"
		addfieldpath="/administrator/components/com_helloworld/models/fields">
	>
		<field
			id="id"
			name="id"
			type="helloworld"
			label="HelloWorld_HelloWorld_Msg_Label"
			description="HelloWorld_HelloWorld_Msg_Desc"
		/>
	</fields>

</metadata>

It introduces a new field type and says Joomla to look for them in the /administrator/components/com_helloworld/models/fields folder.

With your favorite file manager and editor put a file /admin/models/fields/helloworld.php file containing:

site/views/helloworld/tmpl/default.xml

<?php
// No direct access to this file
defined('_JEXEC') or die;
// import the list field type
jimport('joomla.html.html.list');
/**
 * HelloWorld Form Field class for the HelloWorld component
 */
class JFormFieldHelloWorld extends JFormFieldList
{
	/**
	 * The field type.
	 *
	 * @var		string
	 */
	protected $type = 'HelloWorld';
	/**
	 * Method to get a list of options for a list input.
	 *
	 * @return	array		An array of JHtml options.
	 */
	protected function _getOptions() 
	{
		$db = JFactory::getDBO();
		$query = new JQuery;
		$query->select('id,greeting');
		$query->from('#__helloworld');
		$db->setQuery((string)$query);
		$messages = $db->loadObjectList();
		$options = array();
		foreach($messages as $message) 
		{
			$options[] = JHtml::_('select.option', $message->id, $message->greeting);
		}
		$options = array_merge(parent::_getOptions() , $options);
		return $options;
	}
}

Packaging the component

Content of your code directory

• helloworld.xml
• site/index.html
• site/helloworld.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.xml
• site/models/index.html
• site/models/helloworld.php
• 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 add a menu item of this component using the menu manager in the backend.

Contributors

• Christophe Demko