Using the database
Components usually manage their contents using the database. During the install/uninstall/update phase of a component, you can execute SQL queries through the use of SQL text files.With your favorite file manager and editor create two files called admin/sql/install.mysql.utf8.sql and admin/sql/updates/mysql/0.0.6.sql. They should both have the same content, as follows:
admin/sql/install.mysql.utf8.sql and admin/sql/updates/mysql/0.0.6.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!');
Important Note: When the component is installed, the files in the SQL updates folder (for example, admin/sql/updates/mysql) are read and the name of the last file alphabetically is used to populate the component's version number in the
#__schemas
table. This value must be in this table in order for the automatic
update to execute the update SQL files for future versions. For this
reason, it is good practice to create a SQL update file for each version
(even if it is empty or just has a comment). This way the #__schemas version will always match the component version.This is the install file. It will be executed if you put an appropriate order in the helloworld.xml file
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>0.0.6</version>
<!-- The description is optional and defaults to the name -->
<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; 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>
</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>
<!-- tables files section -->
<folder>tables</folder>
<!-- models files section -->
<folder>models</folder>
</files>
</administration>
</extension>
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`;
Adding a new field type
For the moment, we have used a hard coded field 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
name="request"
addfieldpath="/administrator/components/com_helloworld/models/fields"
>
<fieldset name="request">
<field
name="id"
type="helloworld"
label="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_LABEL"
description="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_DESC"
/>
</fieldset>
</fields>
</metadata>
With your favorite file manager and editor put a file admin/models/fields/helloworld.php file containing:
admin/models/fields/helloworld.php
<?php
// No direct access to this file
defined('_JEXEC') or die;
// import the list field type
jimport('joomla.form.helper');
JFormHelper::loadFieldClass('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 = $db->getQuery(true);
$query->select('id,greeting');
$query->from('#__helloworld');
$db->setQuery((string)$query);
$messages = $db->loadObjectList();
$options = array();
if ($messages)
{
foreach($messages as $message)
{
$options[] = JHtml::_('select.option', $message->id, $message->greeting);
}
}
$options = array_merge(parent::getOptions(), $options);
return $options;
}
}
Display the chosen message
When a menu item of this component is created/updated, Joomla stores the identifier of the message. The HelloWorldModelHelloWorld model has now to compute the message according to this identifier and the data stored in the database.Modify the site/models/helloworld.php file:
site/models/helloworld.php
<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
// import Joomla modelitem library
jimport('joomla.application.component.modelitem');
/**
* HelloWorld Model
*/
class HelloWorldModelHelloWorld extends JModelItem
{
/**
* @var array messages
*/
protected $messages;
/**
* Returns a reference to the a Table object, always creating it.
*
* @param type The table type to instantiate
* @param string A prefix for the table class name. Optional.
* @param array Configuration array for model. Optional.
* @return JTable A database object
* @since 2.5
*/
public function getTable($type = 'HelloWorld', $prefix = 'HelloWorldTable', $config = array())
{
return JTable::getInstance($type, $prefix, $config);
}
/**
* Get the message
* @param int The corresponding id of the message to be retrieved
* @return string The message to be displayed to the user
*/
public function getMsg($id = 1)
{
if (!is_array($this->messages))
{
$this->messages = array();
}
if (!isset($this->messages[$id]))
{
//request the selected id
$id = JRequest::getInt('id');
// Get a TableHelloWorld instance
$table = $this->getTable();
// Load the message
$table->load($id);
// Assign the message
$this->messages[$id] = $table->greeting;
}
return $this->messages[$id];
}
}
admin/tables/helloworld.php
<?php
// No direct access
defined('_JEXEC') or die('Restricted access');
// import Joomla table library
jimport('joomla.database.table');
/**
* Hello Table class
*/
class HelloWorldTableHelloWorld extends JTable
{
/**
* Constructor
*
* @param object Database connector object
*/
function __construct(&$db)
{
parent::__construct('#__helloworld', 'id', $db);
}
}
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.xml
- site/views/helloworld/tmpl/default.php
- site/models/index.html
- site/models/helloworld.php
- admin/index.html
- admin/helloworld.php
- admin/sql/index.html
- admin/sql/install.mysql.utf8.sql
- admin/sql/uninstall.mysql.utf8.sql
- admin/sql/updates/index.html
- admin/sql/updates/mysql/index.html
- admin/sql/updates/mysql/0.0.1.sql
- admin/sql/updates/mysql/0.0.6.sql
- admin/models/index.html
- admin/models/fields/index.html
- admin/models/fields/helloworld.php
- admin/tables/index.html
- admin/tables/helloworld.php
Note: site/models/helloworld.php is not up-to-date as mentioned on this page. You need to copy the code yourself.
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