Actions

J2.5

Difference between revisions of "Developing a MVC Component/Adding ACL"

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   `params` TEXT NOT NULL DEFAULT '',
 
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INSERT INTO `#__helloworld` (`greeting`) VALUES
 
INSERT INTO `#__helloworld` (`greeting`) VALUES

Revision as of 16:11, 25 August 2012

This tutorial is for Joomla 2.5


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.

For the moment we leave the deprecated JError-references as they are. They will still be available in Joomla! 3.x. We cannot just change them to JLog::add() statements because in Joomla! 2.5 the messages will then not be enqueued (as there is no messagequeue-logger added as is in /libraries/cms.php in Joomla! 3.0). Other solutions, like using $app->enqueueMessage() or directly throwing PHP-exceptions as showstopper are also possible, but then there would still be numurous references to JError throughout the application. For instance in the view, we now check for errors raised in the model with: count($errors = $this->get('Errors')), which uses JError from the JOBject that was the base for JModel. To be able to use a check like $result instanceof Exception there, we would have to change the way the Model raises those errors and warnings now. If we want to make an application that would work in Joomla! 2.5 and 3.x we can continue using JError. The moment we want to use our 3.x extensions also in 4.x we will have to change this (and probably a lot more too). This tutorial is now primarily focussed on Joomla! 2.5. So: we notice the upcoming change, but leave it there for the moment.

The MVC-base-classes JController, JModel and JView have been changed to JControllerLegacy, JModelLegacy and JViewLegacy to be forward compatibility with Joomla! CMS 3.x legacy classes.

Adding Access Control

With Joomla!'s Access Control we can define which user groups are allowed or denied to do which actions in your component. In this example we use actions that are defined in the core. For the component as a whole: core.admin (access to the configuration) and core.manage (access to the backend). And at various levels actions like create, delete and edit. Besides those core actions you can define your own actions, but that is often not necessary and is not shown in this example. View/Read Access is not managed via those actions but with View Access Levels; see general documentation about Joomla!'s ACL for that.

In the #__assets table the actual list is stored: which user groups are allowed or denied to do which actions on which resources (assets). This is the implementation of the Access Control List (ACL).

In this article we will show how to add and use access permissions at several levels of granularity: for your component as a whole, for the categories and for the individual items.

Minimal ACL requirements at the component level

There are 2 actions that need to be defined at the component level for a Joomla! 2.5 component to offer basic ACL support:

  • Configure (core.admin): which groups are allowed to configure the component level permissions via the 'Options' toolbar button?
  • Access Component (core.manage): which groups are allowed to access the component's backend?

This basic ACL support is done in 4 simple steps:


Add the 2 minimal component level actions to access.xml

Add an access.xml file to the root of the admin folder. Put the 2 basic actions for the com_helloworld component in this file.

admin/access.xml

<?xml version="1.0" encoding="utf-8" ?>
<access component="com_helloworld">
        <section name="component">
                <action name="core.admin" title="JACTION_ADMIN" description="JACTION_ADMIN_COMPONENT_DESC" />
                <action name="core.manage" title="JACTION_MANAGE" description="JACTION_MANAGE_COMPONENT_DESC" />
        </section>
</access>

Add the permissions fieldset to config.xml

Add the following permissions fieldset to admin/config.xml in order to be able to set our component level permissions

        <fieldset
                name="permissions"
                label="JCONFIG_PERMISSIONS_LABEL"
                description="JCONFIG_PERMISSIONS_DESC"
        >
                <field
                        name="rules"
                        type="rules"
                        label="JCONFIG_PERMISSIONS_LABEL"
                        class="inputbox"
                        validate="rules"
                        filter="rules"
                        component="com_helloworld"
                        section="component"
                />
        </fieldset>

See the more elaborate config.xml example further downwards for the exact place where to insert this code.

Add the 'Options' toolbar button when user is authorised for it

Add the following code to admin/views/helloworlds/view.html.php:

    // Options button.
    if (JFactory::getUser()->authorise('core.admin', 'com_helloworld'))     {        JToolBarHelper::preferences('com_helloworld');
    }

See further downwards for a more elaborated example of admin/views/helloworlds/view.html.php where this JToolBarHelper::preferences('com_helloworld') is done in an addToolBar()-method together with the other toolbar buttons and the JUser->authorise()-check is done in the admin/helpers/helloworld.php helper file, resulting in the $canDo-property.

Restrict the access to the component's backend to authorised usergroups

To control the access to the backend of the component add the following lines to the admin/helloworld.php entry-file:

// Access check: is this user allowed to access the backend of this component?
if (!JFactory::getUser()->authorise('core.manage', 'com_helloworld')) 
{
        return JError::raiseWarning(404, JText::_('JERROR_ALERTNOAUTHOR'));
}

See further downwards for the whole code of the admin/helloworld.php file.

Adding more actions, also at category level and item level

When adding more actions and more levels, the above described 4 steps are done too:

In addition we also have to do the following steps:

Describing the actions you want to control the access to

Each component (or part of it) has its own set of permissions that can be controlled. They are described in an access.xml file located at the root of the admin folder. In this helloworld-example the actions to which access is controlled are divided in three sections: at the component level, the category level and the item level. An 'item' is called a 'message' in our example component, hence the name of the third section.

admin/access.xml

<?xml version="1.0" encoding="utf-8" ?>
<access component="com_helloworld">
        <section name="component">
                <action name="core.admin" title="JACTION_ADMIN" description="JACTION_ADMIN_COMPONENT_DESC" />
                <action name="core.manage" title="JACTION_MANAGE" description="JACTION_MANAGE_COMPONENT_DESC" />
                <action name="core.create" title="JACTION_CREATE" description="JACTION_CREATE_COMPONENT_DESC" />
                <action name="core.delete" title="JACTION_DELETE" description="JACTION_DELETE_COMPONENT_DESC" />
                <action name="core.edit" title="JACTION_EDIT" description="JACTION_EDIT_COMPONENT_DESC" />
        </section>
        <section name="category">
                <action name="core.create" title="JACTION_CREATE" description="COM_CATEGORIES_ACCESS_CREATE_DESC" />
                <action name="core.delete" title="JACTION_DELETE" description="COM_CATEGORIES_ACCESS_DELETE_DESC" />
                <action name="core.edit" title="JACTION_EDIT" description="COM_CATEGORIES_ACCESS_EDIT_DESC" />
                <action name="core.edit.state" title="JACTION_EDITSTATE" description="COM_CATEGORIES_ACCESS_EDITSTATE_DESC" />
                <action name="core.edit.own" title="JACTION_EDITOWN" description="COM_CATEGORIES_ACCESS_EDITOWN_DESC" />
        </section>
        <section name="message">
                <action name="core.delete" title="JACTION_DELETE" description="COM_HELLOWORLD_ACCESS_DELETE_DESC" />
                <action name="core.edit" title="JACTION_EDIT" description="COM_HELLOWORLD_ACCESS_EDIT_DESC" />
        </section>
</access>

Adding the setting of permissions in the component's Preferences

Since we now use Access Control permissions in our component, we need to be able to set them at the component level. That is done in the Preferences of this component: the screen you see after clicking the 'Options' button. The config.xml-file is a form-definition for those Preferences. We could define the component level actions here too, as a child of the "rules" field-tag, but it is now preferred to also put those actions in access.xml: in that way all access rules for this component are on one spot.

admin/config.xml

<?xml version="1.0" encoding="utf-8"?>
<config>
        <fieldset
                name="greetings"
                label="COM_HELLOWORLD_CONFIG_GREETING_SETTINGS_LABEL"
                description="COM_HELLOWORLD_CONFIG_GREETING_SETTINGS_DESC"
        >
                <field
                        name="show_category"
                        type="radio"
                        label="COM_HELLOWORLD_HELLOWORLD_FIELD_SHOW_CATEGORY_LABEL"
                        description="COM_HELLOWORLD_HELLOWORLD_FIELD_SHOW_CATEGORY_DESC"
                        default="0"
                >
                        <option value="0">JHIDE</option>
                        <option value="1">JSHOW</option>
                </field>
        </fieldset>
        <fieldset                name="permissions"                label="JCONFIG_PERMISSIONS_LABEL"                description="JCONFIG_PERMISSIONS_DESC"        >                <field                        name="rules"                        type="rules"                        label="JCONFIG_PERMISSIONS_LABEL"                        class="inputbox"                        validate="rules"                        filter="rules"                        component="com_helloworld"                        section="component"                />        </fieldset></config>

Displaying only the right toolbar buttons

Which toolbar buttons to display depends on the Access Control permissions for the user. We put all permissions for this user in the $canDo property of the view; so we can eventually refer to it in layouts (in the edit-form for example).

In the admin/views/helloworlds/view.html.php, put this code

admin/views/helloworlds/view.html.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
 
// import Joomla view library
jimport('joomla.application.component.view');
 
/**
 * HelloWorlds View
 */
class HelloWorldViewHelloWorlds extends JViewLegacy
{
        protected $items;
        protected $pagination;
        protected $canDo; 
        /**
         * HelloWorlds view display method
         * @return void
         */
        function display($tpl = null) 
        {
                // Get data from the model
                $this->items = $this->get('Items');
                $this->pagination = $this->get('Pagination');
 
                // What Access Permissions does this user have? What can (s)he do?                $this->canDo = HelloWorldHelper::getActions(); 
                // Check for errors
                if (count($errors = $this->get('Errors'))) 
                {
                        JError::raiseError(500, implode('<br />', $errors));
                        return false;
                }
 
                // Set the toolbar
                $this->addToolBar();
 
                // Display the template
                parent::display($tpl);
 
                // Set the document
                $this->setDocument();
        }
 
        /**
         * Setting the toolbar
         */
        protected function addToolBar() 
        {
                JToolBarHelper::title(JText::_('COM_HELLOWORLD_MANAGER_HELLOWORLDS'), 'helloworld');
                if ($this->canDo->get('core.create'))                 {                        JToolBarHelper::addNew('helloworld.add', 'JTOOLBAR_NEW');
                }                if ($this->canDo->get('core.edit'))                 {                        JToolBarHelper::editList('helloworld.edit', 'JTOOLBAR_EDIT');
                }                if ($this->canDo->get('core.delete'))                 {                        JToolBarHelper::deleteList('', 'helloworlds.delete', 'JTOOLBAR_DELETE');
                }                if ($this->canDo->get('core.admin'))                 {                        JToolBarHelper::divider();
                        JToolBarHelper::preferences('com_helloworld');
                }        }
        /**
         * Method to set up the document properties
         *
         * @return void
         */
        protected function setDocument() 
        {
                $document = JFactory::getDocument();
                $document->setTitle(JText::_('COM_HELLOWORLD_ADMINISTRATION'));
        }
}

In the admin/views/helloworld/view.html.php, put this code

admin/views/helloworld/view.html.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
 
// import Joomla view library
jimport('joomla.application.component.view');
 
/**
 * HelloWorld View
 */
class HelloWorldViewHelloWorld extends JViewLegacy
{
        protected $form;
        protected $item;
        protected $script;
        protected $canDo; 
        /**
         * display method of Hello view
         * @return void
         */
        public function display($tpl = null) 
        {
                // get the Data
                $this->form = $this->get('Form');
                $this->item = $this->get('Item');
                $this->script = $this->get('Script');
 
                // What Access Permissions does this user have? What can (s)he do?                $this->canDo = HelloWorldHelper::getActions($this->item->id); 
                // Check for errors
                if (count($errors = $this->get('Errors'))) 
                {
                        JError::raiseError(500, implode('<br />', $errors));
                        return false;
                }
 
                // Set the toolbar
                $this->addToolBar();
 
                // Display the template
                parent::display($tpl);
 
                // Set the document
                $this->setDocument();
        }
 
        /**
         * Setting the toolbar
         */
        protected function addToolBar() 
        {
                $input = JFactory::getApplication()->input;
                $input->set('hidemainmenu', true);
                $user = JFactory::getUser();
                $userId = $user->id;
                $isNew = $this->item->id == 0;
                JToolBarHelper::title($isNew ? JText::_('COM_HELLOWORLD_MANAGER_HELLOWORLD_NEW')
                                             : JText::_('COM_HELLOWORLD_MANAGER_HELLOWORLD_EDIT'), 'helloworld');
                // Build the actions for new and existing records.
                if ($isNew) 
                {
                        // For new records, check the create permission.
                        if ($this->canDo->get('core.create'))                         {                                JToolBarHelper::apply('helloworld.apply', 'JTOOLBAR_APPLY');
                                JToolBarHelper::save('helloworld.save', 'JTOOLBAR_SAVE');
                                JToolBarHelper::custom('helloworld.save2new', 'save-new.png', 'save-new_f2.png',
                                                       'JTOOLBAR_SAVE_AND_NEW', false);
                        }                        JToolBarHelper::cancel('helloworld.cancel', 'JTOOLBAR_CANCEL');
                }
                else
                {
                        if ($this->canDo->get('core.edit'))                        {                                // We can save the new record
                                JToolBarHelper::apply('helloworld.apply', 'JTOOLBAR_APPLY');
                                JToolBarHelper::save('helloworld.save', 'JTOOLBAR_SAVE');
 
                                // We can save this record, but check the create permission to see
                                // if we can return to make a new one.
                                if ($this->canDo->get('core.create'))                                 {                                        JToolBarHelper::custom('helloworld.save2new', 'save-new.png', 'save-new_f2.png',
                                                               'JTOOLBAR_SAVE_AND_NEW', false);
                                }                        }                        if ($this->canDo->get('core.create'))                         {                                JToolBarHelper::custom('helloworld.save2copy', 'save-copy.png', 'save-copy_f2.png',
                                                       'JTOOLBAR_SAVE_AS_COPY', false);
                        }                        JToolBarHelper::cancel('helloworld.cancel', 'JTOOLBAR_CLOSE');
                }
        }
        /**
         * Method to set up the document properties
         *
         * @return void
         */
        protected function setDocument() 
        {
                $isNew = $this->item->id == 0;
                $document = JFactory::getDocument();
                $document->setTitle($isNew ? JText::_('COM_HELLOWORLD_HELLOWORLD_CREATING')
                                           : JText::_('COM_HELLOWORLD_HELLOWORLD_EDITING'));
                $document->addScript(JURI::root() . $this->script);
                $document->addScript(JURI::root() . "/administrator/components/com_helloworld"
                                                  . "/views/helloworld/submitbutton.js");
                JText::script('COM_HELLOWORLD_HELLOWORLD_ERROR_UNACCEPTABLE');
        }
}

These two files use the getActions method defined in the admin/helpers/helloworld.php file

In the helper-file, put this code:

admin/helpers/helloworld.php

<?php
// No direct access to this file
defined('_JEXEC') or die;
 
/**
 * HelloWorld component helper.
 */
abstract class HelloWorldHelper
{
        /**
         * Configure the Linkbar.
         */
        public static function addSubmenu($submenu) 
        {
                JSubMenuHelper::addEntry(JText::_('COM_HELLOWORLD_SUBMENU_MESSAGES'),
                                         'index.php?option=com_helloworld', $submenu == 'messages');
                JSubMenuHelper::addEntry(JText::_('COM_HELLOWORLD_SUBMENU_CATEGORIES'),
                                         'index.php?option=com_categories&view=categories&extension=com_helloworld',
                                         $submenu == 'categories');
                // set some global property
                $document = JFactory::getDocument();
                $document->addStyleDeclaration('.icon-48-helloworld ' .
                                               '{background-image: url(../media/com_helloworld/images/tux-48x48.png);}');
                if ($submenu == 'categories') 
                {
                        $document->setTitle(JText::_('COM_HELLOWORLD_ADMINISTRATION_CATEGORIES'));
                }
        }
 
        /**         * Get the actions         */        public static function getActions($messageId = 0)        {                       jimport('joomla.access.access');                $user   = JFactory::getUser();                $result = new JObject;                 if (empty($messageId)) {                        $assetName = 'com_helloworld';                }                else {                        $assetName = 'com_helloworld.message.'.(int) $messageId;                }                 $actions = JAccess::getActions('com_helloworld', 'component');                 foreach ($actions as $action) {                        $result->set($action->name, $user->authorise($action->name, $assetName));                }                 return $result;        }}

Restricting access to the component

The main idea in ACL is to restrict actions to groups of users. The first action to be restricted is access to the administrative backend of the component itself. With your favorite file editor, edit the admin/helloworld.php file and add the lines with the access check.

admin/helloworld.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
 
// Access check: is this user allowed to access the backend of this component?if (!JFactory::getUser()->authorise('core.manage', 'com_helloworld')) {        return JError::raiseWarning(404, JText::_('JERROR_ALERTNOAUTHOR'));} 
// require helper file
JLoader::register('HelloWorldHelper', dirname(__FILE__) . DS . 'helpers' . DS . 'helloworld.php');
 
// import joomla controller library
jimport('joomla.application.component.controller');
 
// Get an instance of the controller prefixed by HelloWorld
$controller = JController::getInstance('HelloWorld');
 
// Perform the Request task
$input = JFactory::getApplication()->input;
$controller->execute($input->getCmd('task'));
 
// Redirect if set by the controller
$controller->redirect();

Add the asset_id column to the database table

In order to be able to work with JTable an asset_id column has to be added to the database #__helloworld table.

So, admin/sql/install.mysql.utf8.sql becomes:

admin/sql/install.mysql.utf8.sql

DROP TABLE IF EXISTS `#__helloworld`;
 
CREATE TABLE `#__helloworld` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `asset_id` INT(10) NOT NULL DEFAULT '0',  `greeting` varchar(25) NOT NULL,
  `catid` int(11) NOT NULL DEFAULT '0',
  `params` TEXT NOT NULL DEFAULT '',
   PRIMARY KEY  (`id`)
);
 
INSERT INTO `#__helloworld` (`greeting`) VALUES
        ('Hello World!'),
        ('Good bye World!');

For updates we add a sql-update-file:

admin/sql/updates/mysql/0.0.14.sql

ALTER TABLE`#__helloworld` ADD COLUMN `asset_id` INT(10) UNSIGNED NOT NULL DEFAULT '0' AFTER `id`;

Setting the permission values in the assets table

In order to store permissions for each message in the assets database table, we have to do two things.

First, in the HelloWorld model we check the 'core.edit' ACL permission: is this user allowed to edit this record? The JUser->autorise() method checks the permission of the record itself and if not set: of it's parent in the assets table.

admin/models/helloworld.php

<?php
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
 
// import Joomla modelform library
jimport('joomla.application.component.modeladmin');
 
/**
 * HelloWorld Model
 */
class HelloWorldModelHelloWorld extends JModelAdmin
{
        /**         * Method override to check if you can edit an existing record.         *         * @param       array   $data   An array of input data.         * @param       string  $key    The name of the key for the primary key.         *         * @return      boolean         * @since       2.5         */        protected function allowEdit($data = array(), $key = 'id')        {                // Check specific edit permission then general edit permission.                return JFactory::getUser()->authorise('core.edit', 'com_helloworld.message.'.                                                      ((int) isset($data[$key]) ? $data[$key] : 0))                       or parent::allowEdit($data, $key);        } 
        /**
         * Returns a reference to the a Table object, always creating it.
         *
         * @param       type    The table type to instantiate
         * @param       string  A prefix for the table class name. Optional.
         * @param       array   Configuration array for model. Optional.
         * @return      JTable  A database object
         * @since       2.5
         */
        public function getTable($type = 'HelloWorld', $prefix = 'HelloWorldTable', $config = array()) 
        {
                return JTable::getInstance($type, $prefix, $config);
        }
 
        /**
         * Method to get the record form.
         *
         * @param       array   $data           Data for the form.
         * @param       boolean $loadData       True if the form is to load its own data (default case), false if not.
         * @return      mixed   A JForm object on success, false on failure
         * @since       2.5
         */
        public function getForm($data = array(), $loadData = true) 
        {
                // Get the form.
                $form = $this->loadForm('com_helloworld.helloworld', 'helloworld',
                                        array('control' => 'jform', 'load_data' => $loadData));
                if (empty($form)) 
                {
                        return false;
                }
                return $form;
        }
 
        /**
         * Method to get the script that has to be included on the form-page
         *
         * @return string       Script files
         */
        public function getScript() 
        {
                return 'administrator/components/com_helloworld/models/forms/helloworld.js';
        }
 
        /**
         * Method to get the data that should be injected in the form.
         *
         * @return      mixed   The data for the form.
         * @since       2.5
         */
        protected function loadFormData() 
        {
                // Check the session for previously entered form data.
                $data = JFactory::getApplication()->getUserState('com_helloworld.edit.helloworld.data', array());
                if (empty($data)) 
                {
                        $data = $this->getItem();
                }
                return $data;
        }
}

Second, we store the item permissions in the assets database table. JTable not only provides an interface for storing the data of the record itself in the item's database table, but also for storing the permissions for that record in the assets database table. Therefore we must add information to the bind()-method about the permission-values. We alsop have to provide the asset name, asset title and the id of the asset parent via the helloworld JTable. Therefore we override 3 methods:

  • _getAssetName(): a unique name for this asset, by which it can be retrieved
  • _getAssetTitle(): a more human-friendly way to identify the asset (not necessary unique)
  • _getAssetParentId(): the asset_id of the parent in the asset database table (from whom permissions are inherited)

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);
        }
 
        /**
         * Overridden bind function
         *
         * @param       array           named array
         * @return      null|string     null if operation was satisfactory, otherwise returns an error
         * @see JTable:bind
         * @since 1.5
         */
        public function bind($array, $ignore = '') 
        {
                if (isset($array['params']) && is_array($array['params'])) 
                {
                        // Convert the params field to a string.
                        $parameter = new JRegistry;
                        $parameter->loadArray($array['params']);
                        $array['params'] = (string)$parameter;
                }
 
                // Bind the rules.                if (isset($array['rules']) && is_array($array['rules']))                {                        $rules = new JAccessRules($array['rules']);                        $this->setRules($rules);                }                 return parent::bind($array, $ignore);        }
 
        /**
         * Overridden load function
         *
         * @param       int $pk primary key
         * @param       boolean $reset reset data
         * @return      boolean
         * @see JTable:load
         */
        public function load($pk = null, $reset = true) 
        {
                if (parent::load($pk, $reset)) 
                {
                        // Convert the params field to a registry.
                        $params = new JRegistry;
                        $params->loadJSON($this->params);
                        $this->params = $params;
                        return true;
                }
                else
                {
                        return false;
                }
        }
 
        /**         * Method to compute the default name of the asset.         * The default name is in the form `table_name.id`         * where id is the value of the primary key of the table.         *         * @return      string         * @since       2.5         */        protected function _getAssetName()        {                $k = $this->_tbl_key;                return 'com_helloworld.message.'.(int) $this->$k;        }         /**         * Method to return the title to use for the asset table.         *         * @return      string         * @since       2.5         */        protected function _getAssetTitle()        {                return $this->greeting;        }         /**         * Method to get the asset-parent-id of the item         *         * @return      int         */        protected function _getAssetParentId()        {                // We will retrieve the parent-asset from the Asset-table                $assetParent = JTable::getInstance('Asset');                // Default: if no asset-parent can be found we take the global asset                $assetParentId = $assetParent->getRootId();                 // Find the parent-asset                if (($this->catid)&& !empty($this->catid))                {                        // The item has a category as asset-parent                        $assetParent->loadByName('com_helloworld.category.' . (int) $this->catid);                }                else                {                        // The item has the component as asset-parent                        $assetParent->loadByName('com_helloworld');                }                 // Return the found asset-parent-id                if ($assetParent->id)                {                        $assetParentId=$assetParent->id;                }                return $assetParentId;        }}

This code for _getAssetParentId() above uses JTableAsset to retrieve the asset_id of the asset-parent. This is different from the code in the current version of com_content, where the asset_id of the category is retrieved from the #__categories database table. That is another possibility; many ways leading to Rome. In com_content however, if an item would not be under a category, then the asset_id of the global asset is returned. That would of course not be right, but is fixed there by providing a default category "uncategorised", so that an article is always under a category. That is why you cannot just copy the code of _getAssetParentId() in com_content to your own component. The code above is more general.

Showing the setting of permissions on the item level

Adding the rules field to the form-definition of the edit-form

admin/models/forms/helloworld.xml

    <fieldset name="accesscontrol">
        <field name="asset_id" type="hidden" filter="unset" />
        <field name="rules"
                type="rules"
                label="JFIELD_RULES_LABEL"
                translate_label="false"
                filter="rules"
                validate="rules"
                class="inputbox"
                component="com_helloworld"
                section="message"
        />
    </fieldset>

And display the ACL interface at the bottom of your Helloworld editform

admin/views/helloworld/tmpl/edit.php

<?php
// No direct access
defined('_JEXEC') or die('Restricted access');
JHtml::_('behavior.tooltip');
JHtml::_('behavior.formvalidation');
$params = $this->form->getFieldsets('params');
?>
<form action="<?php echo JRoute::_('index.php?option=com_helloworld&layout=edit&id='.(int) $this->item->id); ?>"
      method="post" name="adminForm" id="helloworld-form" class="form-validate">
 
   <div class="width-60 fltlft">
      <fieldset class="adminform">
         <legend><?php echo JText::_( 'COM_HELLOWORLD_HELLOWORLD_DETAILS' ); ?></legend>
         <ul class="adminformlist">
            <?php foreach($this->form->getFieldset('details') as $field): ?>
               <li><?php echo $field->label;echo $field->input;?></li>
            <?php endforeach; ?>
         </ul>
      </fieldset>
   </div>
 
   <div class="width-40 fltrt">
      <?php echo JHtml::_('sliders.start', 'helloworld-slider');
         foreach ($params as $name => $fieldset):
            echo JHtml::_('sliders.panel', JText::_($fieldset->label), $name.'-params');
            if (isset($fieldset->description) && trim($fieldset->description)): ?>
               <p class="tip"><?php echo $this->escape(JText::_($fieldset->description));?></p>
            <?php endif;?>
            <fieldset class="panelform" >
               <ul class="adminformlist">
                  <?php foreach ($this->form->getFieldset($name) as $field) : ?>
                     <li><?php echo $field->label; ?><?php echo $field->input; ?></li>
                  <?php endforeach; ?>
               </ul>
            </fieldset>
         <?php endforeach; ?>
 
      <?php echo JHtml::_('sliders.end'); ?>
   </div>
 
   <!-- begin ACL definition-->    <div class="clr"></div>    <?php if ($this->canDo->get('core.admin')): ?>      <div class="width-100 fltlft">         <?php echo JHtml::_('sliders.start', 'permissions-sliders-'.$this->item->id, array('useCookie'=>1)); ?>             <?php echo JHtml::_('sliders.panel', JText::_('COM_HELLOWORLD_FIELDSET_RULES'), 'access-rules'); ?>            <fieldset class="panelform">               <?php echo $this->form->getLabel('rules'); ?>               <?php echo $this->form->getInput('rules'); ?>            </fieldset>          <?php echo JHtml::_('sliders.end'); ?>      </div>   <?php endif; ?>    <!-- end ACL definition--> 
   <div>
      <input type="hidden" name="task" value="helloworld.edit" />
      <?php echo JHtml::_('form.token'); ?>
   </div>
</form>

Adding language strings

We used 3 language strings that have to be added to the backend language-file.

admin/language/en-GB/en-GB.com_helloworld.ini

COM_HELLOWORLD_FIELDSET_RULES="Message Permissions"
COM_HELLOWORLD_ACCESS_DELETE_DESC="Is this group allowed to edit this message?"
COM_HELLOWORLD_ACCESS_DELETE_DESC="Is this group allowed to delete this message?"

Further reading

More information on actions, assets and ACL can be found on the following pages:

Packaging the component

Content of your code directory

Create a compressed file of this directory or directly download the archive (TODO: zip has to be updated! Will be done coming days...) 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.

helloworld.xml

<?xml version="1.0" encoding="utf-8"?>
<extension type="component" version="2.5.0" method="upgrade">
 
        <name>COM_HELLOWORLD</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>0.0.14</version>
        <!-- The description is optional and defaults to the name -->
        <description>COM_HELLOWORLD_DESCRIPTION</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>
                <folder>language</folder>
        </files>
 
        <media destination="com_helloworld" folder="media">
                <filename>index.html</filename>
                <folder>images</folder>
        </media>
 
        <administration>
                <!-- Administration Menu Section -->
                <menu img="../media/com_helloworld/images/tux-16x16.png">COM_HELLOWORLD_MENU</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>config.xml</filename>
                        <filename>access.xml</filename>
                        <filename>helloworld.php</filename>
                        <filename>controller.php</filename>
                        <!-- SQL files section -->
                        <folder>sql</folder>
                        <!-- tables files section -->
                        <folder>tables</folder>
                        <!-- models files section -->
                        <folder>models</folder>
                        <!-- views files section -->
                        <folder>views</folder>
                        <!-- controllers files section -->
                        <folder>controllers</folder>
                        <!-- helpers files section -->
                        <folder>helpers</folder>
                </files>
 
                <languages folder="admin">
                        <language tag="en-GB">language/en-GB/en-GB.com_helloworld.ini</language>
                        <language tag="en-GB">language/en-GB/en-GB.com_helloworld.sys.ini</language>
                </languages>
        </administration>
 
</extension>

Zips

Download the zip file for this Part: [1]= 404!!!, TODO: make new zip available

Navigate

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Contributors

TODO: add