Registering External Plugins in the Apps View

The J2Commerce Apps view (index.php?option=com_j2commerce&view=apps) natively lists plugins from the j2commerce plugin group whose element name starts with app_. The onJ2CommerceRegisterApps event hook extends this to include plugins from any Joomla plugin group — system, content, task, or any other group. Once registered, external plugins appear alongside native app plugins with full support for enable/disable, filtering, sorting, and pagination.

When to Use This Hook

Use this hook when:

• Your plugin lives in the system or another group for technical reasons but is functionally a J2Commerce integration.
• You are building a third-party add-on that store administrators should discover and manage from the J2Commerce Apps view rather than hunting through the global Plugin Manager.
• Your plugin already appears in the j2commerce group under a non-app_ element name (e.g., report_*, payment_*) — those are included natively and do not need this hook.

Architecture

Event Specification

Property	Value
Event name	onJ2CommerceRegisterApps
Dispatched by	AppsModel::getRegisteredExternalAppIds()
Response mechanism	Append to $event->getArgument('result', []) then $event->setArgument('result', $result)
Caching	Per-request ($externalAppIds property, reset between requests)
Validation	IDs cast to int, must be > 0, verified against #__extensions with type = 'plugin'
Safe default	If zero plugins respond or an exception is thrown, the query reverts to the unmodified native-only WHERE clause

The event is dispatched using Joomla's standard GenericEvent. Do not use $event->addResult() — that method does not exist on GenericEvent. Instead, read the current result argument, append your entry, and write it back with setArgument(). The response array key must be exactly extension_id. Any other keys in the array are ignored.

Complete Working Example

The following files implement a minimal system plugin that registers itself in the Apps view. Adapt the namespace, element name, and file paths to your own plugin.

Plugin Class

<?php
// File: plugins/system/mymyintegration/src/Extension/MymyIntegration.php

declare(strict_types=1);

namespace Acme\Plugin\System\MymyIntegration\Extension;

\defined('_JEXEC') or die;

use Joomla\CMS\Plugin\CMSPlugin;
use Joomla\Database\DatabaseAwareTrait;
use Joomla\Event\Event;
use Joomla\Event\SubscriberInterface;

final class MymyIntegration extends CMSPlugin implements SubscriberInterface
{
    use DatabaseAwareTrait;

    public $autoloadLanguage = true;

    public static function getSubscribedEvents(): array
    {
        return [
            'onJ2CommerceRegisterApps' => 'onRegisterApps',
        ];
    }

    public function onRegisterApps(Event $event): void
    {
        $db    = $this->getDatabase();
        $query = $db->getQuery(true)
            ->select($db->quoteName('extension_id'))
            ->from($db->quoteName('#__extensions'))
            ->where($db->quoteName('type') . ' = ' . $db->quote('plugin'))
            ->where($db->quoteName('folder') . ' = ' . $db->quote('system'))
            ->where($db->quoteName('element') . ' = ' . $db->quote('mymyintegration'));

        $extensionId = (int) $db->setQuery($query)->loadResult();

        if ($extensionId > 0) {
            $result = $event->getArgument('result', []);
            $result[] = ['extension_id' => $extensionId];
            $event->setArgument('result', $result);
        }
    }
}

The handler queries the database for its own extension_id rather than hard-coding a value. This is safe for multi-site installations and survives reinstall without ID changes.

Service Provider

<?php
// File: plugins/system/mymyintegration/services/provider.php

\defined('_JEXEC') or die;

use Acme\Plugin\System\MymyIntegration\Extension\MymyIntegration;
use Joomla\CMS\Extension\PluginInterface;
use Joomla\CMS\Factory;
use Joomla\CMS\Plugin\PluginHelper;
use Joomla\DI\Container;
use Joomla\Database\DatabaseInterface;
use Joomla\DI\ServiceProviderInterface;
use Joomla\Event\DispatcherInterface;

return new class implements ServiceProviderInterface
{
    public function register(Container $container): void
    {
        $container->set(
            PluginInterface::class,
            function (Container $container) {
                $plugin = new MymyIntegration(
                    $container->get(DispatcherInterface::class),
                    (array) PluginHelper::getPlugin('system', 'mymyintegration')
                );
                $plugin->setApplication(Factory::getApplication());
                $plugin->setDatabase($container->get(DatabaseInterface::class));
                return $plugin;
            }
        );
    }
};

XML Manifest

<?xml version="1.0" encoding="utf-8"?>
<extension type="plugin" group="system" method="upgrade">
    <name>PLG_SYSTEM_MYMYINTEGRATION</name>
    <author>Acme Corp</author>
    <version>1.0.0</version>
    <description>PLG_SYSTEM_MYMYINTEGRATION_XML_DESCRIPTION</description>
    <namespace path="src">Acme\Plugin\System\MymyIntegration</namespace>
    <files>
        <folder plugin="mymyintegration">services</folder>
        <folder>src</folder>
        <folder>language</folder>
        <folder>media</folder>
    </files>
    <languages folder="language">
        <language tag="en-GB">en-GB/plg_system_mymyintegration.ini</language>
        <language tag="en-GB">en-GB/plg_system_mymyintegration.sys.ini</language>
    </languages>
    <media destination="plg_system_mymyintegration" folder="media">
        <folder>images</folder>
    </media>
</extension>

Language File

; File: plugins/system/mymyintegration/language/en-GB/plg_system_mymyintegration.ini

PLG_SYSTEM_MYMYINTEGRATION="My Integration"
PLG_SYSTEM_MYMYINTEGRATION_XML_DESCRIPTION="Integrates My Service with J2Commerce."

The <name> language key is what appears in the Name column of the Apps view. The <description> language key is shown as the truncated description text below the plugin name.

Plugin Image

Place a 300×200 px .webp image at:

media/plg_system_mymyintegration/images/mymyintegration.webp

The image filename must match the plugin element name. The Apps view template resolves images using this pattern:

media/plg_{folder}_{element}/images/{element}.{jpg|png|webp}

It checks .jpg, .png, and .webp in that order. If no image is found, a placeholder is displayed. The media/ folder under the plugin source is copied to the Joomla root media/ directory during installation, provided the manifest declares a <media> section as shown above.

How the Apps View Handles External Plugins

SQL WHERE Clause Expansion

AppsModel::getListQuery() calls getRegisteredExternalAppIds() before building its query. When one or more external IDs are returned, the native clause:

WHERE a.folder = 'j2commerce' AND a.element LIKE 'app_%'

is replaced by:

WHERE (
    (a.folder = 'j2commerce' AND a.element LIKE 'app_%')
    OR a.extension_id IN (:extId0, :extId1, ...)
)

All filtering (enabled state, plugin type, search), sorting, and pagination continue to work at the database level without modification.

Image Resolution

The template resolves the image path using $item->folder and $item->element, which are pulled directly from #__extensions. The lookup sequence is:

1. media/plg_{folder}_{element}/images/{element}.jpg
2. media/plg_{folder}_{element}/images/{element}.png
3. media/plg_{folder}_{element}/images/{element}.webp
4. plugins/{folder}/{element}/images/{element}.png (legacy fallback)
5. media/com_j2commerce/images/{element}.png (legacy fallback)
6. media/com_j2commerce/images/default_app_j2commerce.webp (final fallback)

Language Loading

HtmlView::loadAppPluginLanguages() loads language files for both native and external plugins before the list renders. For an external plugin with folder system and element mymyintegration it loads:

$lang->load('plg_system_mymyintegration', JPATH_ADMINISTRATOR)
    || $lang->load('plg_system_mymyintegration', JPATH_PLUGINS . '/system/mymyintegration');

This means Text::_($item->name) and Text::_($item->description) resolve correctly in the list even though the plugin is not in the j2commerce group.

Edit Link Routing

All plugins — both native j2commerce group and external — open in the standard Joomla Plugin Manager (index.php?option=com_plugins&task=plugin.edit&extension_id=N) when the user clicks their name or image. There is no separate J2Commerce app editor view.

Source Badge

When $item->folder is not j2commerce, the template renders a small Bootstrap badge bg-info next to the plugin name showing the folder:

My Integration  [system]

This distinguishes external plugins from native J2Commerce app plugins at a glance.

Requirements Checklist

Before the hook works correctly, verify all of the following:

• Plugin is installed and enabled in Joomla (visible in System -> Manage -> Plugins)
• Plugin class uses DatabaseAwareTrait and service provider calls $plugin->setDatabase()
• getSubscribedEvents() maps onJ2CommerceRegisterApps to a valid method name
• The handler appends to $event->getArgument('result', []) and calls $event->setArgument('result', $result) with a positive integer extension_id
• The extension_id exists in #__extensions with type = 'plugin'
• Language file is named plg_{folder}_{element}.ini and contains the PLG_* name and description language keys
• Plugin image is placed at media/plg_{folder}_{element}/images/{element}.webp (or .jpg / .png)
• Manifest <media> section declares the images folder so Joomla copies it to the root media/ directory on install

Troubleshooting

Plugin does not appear in the Apps view

1. Missing DatabaseAwareTrait: Your plugin class must use DatabaseAwareTrait; and your service provider must call $plugin->setDatabase($container->get(DatabaseInterface::class)). Without both, $this->getDatabase() throws Call to undefined method, which AppsModel catches silently — the plugin just doesn't appear with no visible error.
2. Using $event->addResult(): GenericEvent does not have an addResult() method. This throws Call to undefined method, again caught silently. Use getArgument()/setArgument() as shown in the example above.
3. Confirm the plugin is enabled in the Plugin Manager. Disabled plugins still receive events, but AppsModel verifies the returned ID against #__extensions — a disabled plugin still has a valid record and will be included. If it is not appearing at all, the ID returned by your handler is likely 0 (plugin not found in the database).
4. Check the element name and folder passed to your database query match exactly what is in #__extensions. Use DESCRIBE j6__extensions or query SELECT folder, element, extension_id FROM j6__extensions WHERE type = 'plugin' AND element LIKE '%myintegration%' to confirm.
5. The onJ2CommerceRegisterApps event is only dispatched when the Apps view is loaded. It is not fired on other pages.

Plugin name shows as a language key (not translated)

The Apps view loads language files before rendering the list, but only for plugins whose extension_id was returned by getRegisteredExternalAppIds(). If your language file is not loading:

1. Verify the file is named exactly plg_{folder}_{element}.ini — the naming is case-sensitive on Linux hosts.
2. Confirm the language file is present in administrator/language/en-GB/ at the Joomla root (not only inside the plugin directory). Installation via the manifest <languages> tag copies it there; manually installed plugins may need this done manually.
3. If testing before installation, place the file directly at JPATH_ADMINISTRATOR/language/en-GB/plg_system_mymyintegration.ini.

Plugin image shows the placeholder instead of my image

1. Confirm the image is at media/plg_{folder}_{element}/images/{element}.webp under the Joomla root media/ directory — not under plugins/. The manifest <media> section copies it there during installation.
2. Check the filename matches the element name exactly: for folder system and element mymyintegration, the file must be mymyintegration.webp.
3. If you installed manually (not via the installer), copy the file from plugins/system/mymyintegration/media/images/mymyintegration.webp to media/plg_system_mymyintegration/images/mymyintegration.webp.

Edit link opens the wrong page

External plugins (any folder other than j2commerce) always route to the standard Joomla Plugin Manager editor (com_plugins&task=plugin.edit). This is intentional. If you want a custom configuration interface, build it as a separate admin view in your own component and link to it from within the Plugin Manager edit form.

Source File Reference

File	Description
administrator/components/com_j2commerce/src/Model/AppsModel.php	getRegisteredExternalAppIds() dispatches the event; getListQuery() expands the WHERE clause
administrator/components/com_j2commerce/src/View/Apps/HtmlView.php	loadAppPluginLanguages() loads language files for both native and external plugins
administrator/components/com_j2commerce/tmpl/apps/default.php	Renders the plugin list; resolves images, edit links, and source badge using $item->folder

Related

• Dashboard Plugin Events
• Dashboard Extensions