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{{underconstruction}}
+
{{version/tutor|2.5}}
{{future|1.6}}
+
{{Chunk:Developing a Model-View-Controller (MVC) Component for Joomla!2.5 - Contents}}
 
 
== Articles in this series ==
 
{{Chunk:Developing a Model-View-Controller (MVC) Component for Joomla!1.6 - Contents}}
 
  
 
== Introduction ==
 
== 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.
+
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.
  
 
== Using the database ==
 
== 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.
 
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 put a file ''admin/sql/install.mysql.utf8.sql'' containing:
+
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:
  
 
<span id="admin/sql/install.mysql.utf8.sql">
 
<span id="admin/sql/install.mysql.utf8.sql">
''admin/sql/install.mysql.utf8.sql''
+
''admin/sql/install.mysql.utf8.sql'' and ''admin/sql/updates/mysql/0.0.6.sql''
 
<source lang="sql">
 
<source lang="sql">
 
DROP TABLE IF EXISTS `#__helloworld`;
 
DROP TABLE IF EXISTS `#__helloworld`;
  
 
CREATE TABLE `#__helloworld` (
 
CREATE TABLE `#__helloworld` (
`id` INT(11) NOT NULL auto_increment,
+
  `id` int(11) NOT NULL auto_increment,
`greeting` VARCHAR(25) NOT NULL,
+
  `greeting` varchar(25) NOT NULL,
PRIMARY KEY  (`id`)
+
  PRIMARY KEY  (`id`)
 
) ENGINE=MyISAM AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;
 
) ENGINE=MyISAM AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;
  
Line 30: Line 27:
 
</span>
 
</span>
  
This is the install file. It will be executed if your put an appropriate order in the ''helloworld.xml'' file
+
The file ''install.mysql.utf8.sql'' will be executed when you install this component. The file ''0.0.6.sql'' is executed when you do an update.
 +
 
 +
'''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 <code>#__schemas</code> 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 <code>#__schemas</code> version will always match the component version.
 +
 
 +
'''Important Note:''' When saving the SQL files in utf8, be sure to save them as utf8 NO BOM or the query will fail with MySQL error #1064.
 +
 
 +
This is the install file. It will be executed if you put an appropriate order in the ''helloworld.xml'' file
  
 
<span id="helloworld.xml">
 
<span id="helloworld.xml">
Line 36: Line 39:
 
<source lang="xml">
 
<source lang="xml">
 
<?xml version="1.0" encoding="utf-8"?>
 
<?xml version="1.0" encoding="utf-8"?>
<extension type="component" version="1.6.0" method="upgrade">
+
<extension type="component" version="2.5.0" method="upgrade">
 +
 
 
<name>Hello World!</name>
 
<name>Hello World!</name>
 +
<!-- The following elements are optional and free of formatting constraints -->
 
<creationDate>November 2009</creationDate>
 
<creationDate>November 2009</creationDate>
 
<author>John Doe</author>
 
<author>John Doe</author>
Line 44: Line 49:
 
<copyright>Copyright Info</copyright>
 
<copyright>Copyright Info</copyright>
 
<license>License Info</license>
 
<license>License Info</license>
 +
<!--  The version string is recorded in the components table -->
 
<version>0.0.6</version>
 
<version>0.0.6</version>
 +
<!-- The description is optional and defaults to the name -->
 
<description>Description of the Hello World component ...</description>
 
<description>Description of the Hello World component ...</description>
  
Line 57: Line 64:
 
</sql>
 
</sql>
 
</uninstall>
 
</uninstall>
<update> <!-- Runs on update -->
+
<update> <!-- Runs on update; New in 2.5 -->
 
<schemas>
 
<schemas>
 
<schemapath type="mysql">sql/updates/mysql</schemapath>
 
<schemapath type="mysql">sql/updates/mysql</schemapath>
Line 63: Line 70:
 
</update>
 
</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">
 
<files folder="site">
 
<filename>index.html</filename>
 
<filename>index.html</filename>
Line 72: Line 83:
  
 
<administration>
 
<administration>
 +
<!-- Administration Menu Section -->
 
<menu>Hello World!</menu>
 
<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">
 
<files folder="admin">
 +
<!-- Admin Main File Copy Section -->
 
<filename>index.html</filename>
 
<filename>index.html</filename>
 
<filename>helloworld.php</filename>
 
<filename>helloworld.php</filename>
Line 82: Line 99:
 
<!-- models files section -->
 
<!-- models files section -->
 
<folder>models</folder>
 
<folder>models</folder>
</files>
+
</files>
 
</administration>
 
</administration>
 +
 
</extension>
 
</extension>
 
</source>
 
</source>
Line 98: Line 116:
 
</source>
 
</source>
 
</span>
 
</span>
 
And finally, create a folder for storing updates in the future ''admin/sql/updates/mysql''
 
  
 
== Adding a new field type ==
 
== Adding a new field type ==
For the moment, we have used a [[Developing_a_Model-View-Controller_%28MVC%29_Component_for_Joomla!1.6_-_Part_03|hard coded field type for messages]]. We need to use our database for choosing the message.
+
For the moment, we have used a [[Developing_a_Model-View-Controller_%28MVC%29_Component_for_Joomla!2.5_-_Part_03|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
 
Modify the ''site/views/helloworld/tmpl/default.xml'' file and put these lines
Line 110: Line 126:
 
<source lang="xml">
 
<source lang="xml">
 
<?xml version="1.0" encoding="utf-8"?>
 
<?xml version="1.0" encoding="utf-8"?>
 
<!-- $Id: default.xml 37 2010-11-19 15:01:11Z chdemko $ -->
 
 
 
<metadata>
 
<metadata>
 
 
<layout title="COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_TITLE">
 
<layout title="COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_TITLE">
 
 
<message>COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_DESC</message>
 
<message>COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_DESC</message>
 
 
</layout>
 
</layout>
 
<fields
 
<fields
Line 128: Line 138:
 
name="id"
 
name="id"
 
type="helloworld"
 
type="helloworld"
label="COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_MSG_LABEL"
+
label="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_LABEL"
description="COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_MSG_DESC"
+
description="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_DESC"
 
/>
 
/>
 
</fieldset>
 
</fieldset>
 
</fields>
 
</fields>
 
 
</metadata>
 
</metadata>
 
</source>
 
</source>
Line 148: Line 157:
 
// No direct access to this file
 
// No direct access to this file
 
defined('_JEXEC') or die;
 
defined('_JEXEC') or die;
 +
 
// import the list field type
 
// import the list field type
jimport('joomla.html.html.list');
+
jimport('joomla.form.helper');
 +
JFormHelper::loadFieldClass('list');
 +
 
 
/**
 
/**
 
  * HelloWorld Form Field class for the HelloWorld component
 
  * HelloWorld Form Field class for the HelloWorld component
Line 161: Line 173:
 
*/
 
*/
 
protected $type = 'HelloWorld';
 
protected $type = 'HelloWorld';
 +
 
/**
 
/**
 
* Method to get a list of options for a list input.
 
* Method to get a list of options for a list input.
Line 172: Line 185:
 
$query->select('id,greeting');
 
$query->select('id,greeting');
 
$query->from('#__helloworld');
 
$query->from('#__helloworld');
$db->setQuery($query);
+
$db->setQuery((string)$query);
 
$messages = $db->loadObjectList();
 
$messages = $db->loadObjectList();
 
$options = array();
 
$options = array();
foreach($messages as $message)  
+
if ($messages)
 
{
 
{
$options[] = JHtml::_('select.option', $message->id, $message->greeting);
+
foreach($messages as $message)
 +
{
 +
$options[] = JHtml::_('select.option', $message->id, $message->greeting);
 +
}
 
}
 
}
$options = array_merge(parent::getOptions() , $options);
+
$options = array_merge(parent::getOptions(), $options);
 
return $options;
 
return $options;
 
}
 
}
Line 199: Line 215:
 
// No direct access to this file
 
// No direct access to this file
 
defined('_JEXEC') or die('Restricted access');
 
defined('_JEXEC') or die('Restricted access');
 +
 
// import Joomla modelitem library
 
// import Joomla modelitem library
 
jimport('joomla.application.component.modelitem');
 
jimport('joomla.application.component.modelitem');
 +
 
/**
 
/**
 
  * HelloWorld Model
 
  * HelloWorld Model
Line 207: Line 225:
 
{
 
{
 
/**
 
/**
* @var string msg
+
* @var array messages
 
*/
 
*/
protected $msg;
+
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
 
* Get the message
 +
* @param  int    The corresponding id of the message to be retrieved
 
* @return string The message to be displayed to the user
 
* @return string The message to be displayed to the user
 
*/
 
*/
public function getMsg()  
+
public function getMsg($id = 1)  
 
{
 
{
if (!isset($this->msg))  
+
if (!is_array($this->messages))
 +
{
 +
$this->messages = array();
 +
}
 +
 +
if (!isset($this->messages[$id]))  
 
{
 
{
$id = JRequest::getInt('id');
+
                        //request the selected id
 +
$jinput = JFactory::getApplication()->input;
 +
$id = $jinput->get('id', 1, 'INT' );
 +
 
 
// Get a TableHelloWorld instance
 
// Get a TableHelloWorld instance
 
$table = $this->getTable();
 
$table = $this->getTable();
 +
 
// Load the message
 
// Load the message
 
$table->load($id);
 
$table->load($id);
 +
 
// Assign the message
 
// Assign the message
$this->msg = $table->greeting;
+
$this->messages[$id] = $table->greeting;
 
}
 
}
return $this->msg;
+
 +
return $this->messages[$id];
 
}
 
}
 
}
 
}
Line 240: Line 284:
 
// No direct access
 
// No direct access
 
defined('_JEXEC') or die('Restricted access');
 
defined('_JEXEC') or die('Restricted access');
 +
 
// import Joomla table library
 
// import Joomla table library
 
jimport('joomla.database.table');
 
jimport('joomla.database.table');
Line 248: Line 293:
 
class HelloWorldTableHelloWorld extends JTable
 
class HelloWorldTableHelloWorld extends JTable
 
{
 
{
 
/**
 
* Primary Key
 
*
 
* @var int
 
*/
 
var $id = null;
 
 
/**
 
* @var string
 
*/
 
var $greeting = null;
 
 
 
/**
 
/**
 
* Constructor
 
* Constructor
Line 266: Line 298:
 
* @param object Database connector object
 
* @param object Database connector object
 
*/
 
*/
function __construct(&$db)
+
function __construct(&$db)  
 
{
 
{
 
parent::__construct('#__helloworld', 'id', $db);
 
parent::__construct('#__helloworld', 'id', $db);
Line 280: Line 312:
 
Content of your code directory
 
Content of your code directory
 
* ''[[#helloworld.xml|helloworld.xml]]''
 
* ''[[#helloworld.xml|helloworld.xml]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|site/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|site/index.html]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_02#site/helloworld.php|site/helloworld.php]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_02#site/helloworld.php|site/helloworld.php]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_02#site/controller.php|site/controller.php]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_02#site/controller.php|site/controller.php]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|site/views/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|site/views/index.html]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|site/views/helloworld/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|site/views/helloworld/index.html]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_04#site/views/helloworld/view.html.php|site/views/helloworld/view.html.php]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_04#site/views/helloworld/view.html.php|site/views/helloworld/view.html.php]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|site/views/helloworld/tmpl/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|site/views/helloworld/tmpl/index.html]]''
 
* ''[[#site/views/helloworld/tmpl/default.xml|site/views/helloworld/tmpl/default.xml]]''
 
* ''[[#site/views/helloworld/tmpl/default.xml|site/views/helloworld/tmpl/default.xml]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_02#site/views/helloworld/tmpl/default.php|site/views/helloworld/tmpl/default.php]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_02#site/views/helloworld/tmpl/default.php|site/views/helloworld/tmpl/default.php]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|site/models/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|site/models/index.html]]''
 
* ''[[#site/models/helloworld.php|site/models/helloworld.php]]''
 
* ''[[#site/models/helloworld.php|site/models/helloworld.php]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|admin/index.html]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#admin/helloworld.php|admin/helloworld.php]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#admin/helloworld.php|admin/helloworld.php]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/sql/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|admin/sql/index.html]]''
 
* ''[[#admin/sql/install.mysql.utf8.sql|admin/sql/install.mysql.utf8.sql]]''
 
* ''[[#admin/sql/install.mysql.utf8.sql|admin/sql/install.mysql.utf8.sql]]''
 
* ''[[#admin/sql/uninstall.mysql.utf8.sql|admin/sql/uninstall.mysql.utf8.sql]]''
 
* ''[[#admin/sql/uninstall.mysql.utf8.sql|admin/sql/uninstall.mysql.utf8.sql]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/sql/updates/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|admin/sql/updates/index.html]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/sql/updates/mysql/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|admin/sql/updates/mysql/index.html]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/models/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#admin/sql/updates/mysql/0.0.1.sql|admin/sql/updates/mysql/0.0.1.sql]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/models/fields/index.html]]''
+
* ''[[#admin/sql/install.mysql.utf8.sql|admin/sql/updates/mysql/0.0.6.sql]]''
 +
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|admin/models/index.html]]''
 +
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|admin/models/fields/index.html]]''
 
* ''[[#admin/models/fields/helloworld.php|admin/models/fields/helloworld.php]]''
 
* ''[[#admin/models/fields/helloworld.php|admin/models/fields/helloworld.php]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/tables/index.html]]''
+
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!2.5_-_Part_01#index.html|admin/tables/index.html]]''
 
* ''[[#admin/tables/helloworld.php|admin/tables/helloworld.php]]''
 
* ''[[#admin/tables/helloworld.php|admin/tables/helloworld.php]]''
  
Create a compressed file of this directory or directly download the [http://joomlacode.org/gf/download/frsrelease/11394/46144/com_helloworld-1.6-part06.zip 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.
+
Create a compressed file of this directory or directly download the [http://joomlacode.org/gf/download/frsrelease/11394/58405/com_helloworld-1.6-part06.zip 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.
 +
 
 +
Note: site/models/helloworld.php is not up-to-date as mentioned on this page. You need to copy the code yourself.
  
 
== Navigate ==
 
== Navigate ==
  
[[Developing a Model-View-Controller (MVC) Component for Joomla!1.6 - Part 05|Prev: Adding a variable request in the menu type]]
+
[[Developing a Model-View-Controller (MVC) Component for Joomla!2.5 - Part 05|Prev: Adding a variable request in the menu type]]
[[Developing a Model-View-Controller (MVC) Component for Joomla!1.6 - Part 07|Next: Basic backend]]
+
[[Developing a Model-View-Controller (MVC) Component for Joomla!2.5 - Part 07|Next: Basic backend]]
  
 
== Contributors ==
 
== Contributors ==
 
*[[User:cdemko|Christophe Demko]]
 
*[[User:cdemko|Christophe Demko]]
 +
*[[User:oaksu|Ozgur Aksu]]
  
 
[[Category:Development]]
 
[[Category:Development]]
[[category:Joomla! 1.6]]
+
[[Category:Joomla! 1.6]]
[[category:Manual]]
+
[[Category:Joomla! 1.7]]
 +
[[Category:Joomla! 2.5]]
  
 
''Italic text''
 
''Italic text''

Revision as of 14:46, 3 May 2013

This page has been archived. This page contains information for an unsupported Joomla! version or is no longer relevant. It exists only as a historical reference, it will not be improved and its content may be incomplete and/or contain broken links.


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.

Using the database[edit]

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!');

The file install.mysql.utf8.sql will be executed when you install this component. The file 0.0.6.sql is executed when you do an update.

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.

Important Note: When saving the SQL files in utf8, be sure to save them as utf8 NO BOM or the query will fail with MySQL error #1064.

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>

Do the same for the uninstall 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`;

Adding a new field type[edit]

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>

It introduces a new field type and tells Joomla to look for the field definition 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:

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;
	}
}

The new field type displays a drop-down list of messages to choose from. You can see the result of this change in the menu manager section for the helloworld item.

Display the chosen message[edit]

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
			$jinput = JFactory::getApplication()->input;
			$id = $jinput->get('id', 1, 'INT' );

			// 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];
	}
}

The model now asks the TableHelloWorld to get the message. This table class has to be defined in admin/tables/helloworld.php file

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);
	}
}

You shouldn't see any differences, but if you access the database you should see a table named jos_helloworld with two columns: id and greeting. And two entries: Hello World! and Good bye World

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.

Note: site/models/helloworld.php is not up-to-date as mentioned on this page. You need to copy the code yourself.

Navigate[edit]

Prev: Adding a variable request in the menu type Next: Basic backend

Contributors[edit]

Italic text