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

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(Packaging the component)
m (Correction for "messages" variable array in site/models/helloworld.php)
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{{future|1.6}}
+
{{version/tutor|2.5}}
 
+
{{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 two files ''admin/sql/install.mysql.utf8.sql'' and ''admin/sql/updates/mysql/0.0.6.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">
Line 29: 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.
 +
 
 +
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 35: Line 37:
 
<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 conttraints -->
+
<!-- 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 60: Line 62:
 
</sql>
 
</sql>
 
</uninstall>
 
</uninstall>
<update> <!-- Runs on update; New in 1.6 -->
+
<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 114: Line 116:
  
 
== 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 126: Line 128:
 
<message>COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_DESC</message>
 
<message>COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_DESC</message>
 
</layout>
 
</layout>
<fields name="request">
+
<fields
 +
name="request"
 +
addfieldpath="/administrator/components/com_helloworld/models/fields"
 +
>
 
<fieldset name="request">
 
<fieldset name="request">
 
<field
 
<field
 
name="id"
 
name="id"
type="list"
+
type="helloworld"
 
label="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_LABEL"
 
label="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_LABEL"
 
description="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_DESC"
 
description="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_DESC"
default="1"
+
/>
>
+
<option value="1">Hello World!</option>
+
<option value="2">Good bye World!</option>
+
</field>
+
 
</fieldset>
 
</fieldset>
 
</fields>
 
</fields>
Line 156: Line 157:
  
 
// import the list field type
 
// import the list field type
jimport('joomla.html.html.list');
+
jimport('joomla.form.helper');
 +
JFormHelper::loadFieldClass('list');
  
 
/**
 
/**
Line 184: Line 186:
 
$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);
Line 218: Line 223:
 
{
 
{
 
/**
 
/**
* @var string msg
+
* @var array messages
 
*/
 
*/
protected $msg;
+
protected $messages;
  
 
/**
 
/**
Line 229: Line 234:
 
* @param array Configuration array for model. Optional.
 
* @param array Configuration array for model. Optional.
 
* @return JTable A database object
 
* @return JTable A database object
* @since 1.6
+
* @since 2.5
 
*/
 
*/
 
public function getTable($type = 'HelloWorld', $prefix = 'HelloWorldTable', $config = array())  
 
public function getTable($type = 'HelloWorld', $prefix = 'HelloWorldTable', $config = array())  
Line 237: Line 242:
 
/**
 
/**
 
* 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]))
 +
{
 +
                        //request the selected id
 
$id = JRequest::getInt('id');
 
$id = JRequest::getInt('id');
 +
 
// Get a TableHelloWorld instance
 
// Get a TableHelloWorld instance
 
$table = $this->getTable();
 
$table = $this->getTable();
Line 251: Line 264:
  
 
// Assign the message
 
// Assign the message
$this->msg = $table->greeting;
+
$this->messages[$id] = $table->greeting;
 
}
 
}
return $this->msg;
+
 +
return $this->messages[$id];
 
}
 
}
 
}
 
}
Line 295: Line 309:
 
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#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!2.5_-_Part_01#admin/sql/updates/mysql/0.0.1.sql|admin/sql/updates/mysql/0.0.1.sql]]''
 
* ''[[#admin/sql/install.mysql.utf8.sql|admin/sql/updates/mysql/0.0.6.sql]]''
 
* ''[[#admin/sql/install.mysql.utf8.sql|admin/sql/updates/mysql/0.0.6.sql]]''
* ''[[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#index.html|admin/models/index.html]]''
* ''[[Developing_a_Model-View-Controller_(MVC)_Component_for_Joomla!1.6_-_Part_01#index.html|admin/models/fields/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/11394/58121/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 21:04, 5 December 2012


Introduction

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

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.

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

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

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];
        }
}

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

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

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

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