Difference between revisions of "Developing a MVC Component/Using the database"

Revision as of 06:23, 9 November 2009

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Under Construction

Articles in this serie[edit]

Indroduction[edit]

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[edit]

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[edit]

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[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!1.6. You can add a menu item of this component using the menu manager in the backend.

Contributors[edit]

Christophe Demko

Archived