Module Events

Module Events are triggered when Joomla processes the modules to obtain the HTML output to include in the HTTP response.

For a plugin to capture these events it should be defined as a system plugin.

warning

System plugins are loaded every time Joomla runs, on both the site front-end and administrator back-end. If you have a PHP syntax error in a system plugin then you will get locked out of the Joomla administrator back-end, and will have to go into phpmyadmin (or equivalent) to set to 0 the enabled field within the plugin record in the #__extensions table.

For background on Joomla transitioning to using classes for events see Joomla 4 and 5 changes, where you can also find explanations for accessing the arguments and returning values.

Joomla Overview

Joomla processes the modules after it has obtained the component output and determined the template to use, and is processing elements such as <jdoc:include type="modules" name="topbar" style="none" /> within the template file (eg templates/cassiopeia/index.php).

There are 2 stages to Joomla obtaining the module output:

1. It obtains the list of modules which should be displayed on the requested web page

2. It renders each of these modules. (In other words, it runs each of these modules to obtain its output, and then includes the output in the HTML to return to the client.)

Obtaining the List of Modules

This is handled in ModuleHelper::load() (in libraries/src/Helper/ModuleHelper.php).

• trigger onPrepareModuleList - your plugin can return a list of modules, and then Joomla will use your list instead of performing the next step
• Joomla reads from the database the list of modules to display, taking into account the Module Menu Assignment options, but only those where the module is included on pages
• trigger onAfterModuleList - your plugin can update the list of modules
• Joomla cleans the module list, by removing those which the Module Menu Assignment options define as being excluded on this page
• trigger onAfterCleanModuleList - your plugin can update the list of modules

After this, Joomla has the definitive set of modules to use for the requested web page.

Rendering the Modules

Joomla processes in turn each <jdoc:include type="modules" name=<template position>...> in the template file, and this will involve rendering each of the modules which is using that template position.

For each template position Joomla does the following:

• For each module using that template position

  • run the module and capture its raw output
  • trigger onRenderModule
  • add the HTML wrapper (chrome style) as defined in the Module Advanced tab / Module Style (if set to "Inherited" then it will use the style defined in the template file)
  • trigger onAfterRenderModule
  • add the HTML to the buffer containing the HTML for that template position

• Then (after all the modules for a template position have been rendered) trigger onAfterRenderModules

onPrepareModuleList

Description

This event is triggered before Joomla obtains the list of modules to run.

You can use this event to define the modules which Joomla will use.

Event Arguments

The event class \Joomla\CMS\Event\Module\PrepareModuleListEvent has the following arguments:

• modules - the array of modules (which at this stage is an empty array)

• subject - null (not used)

Return Value

You can update the set of modules which Joomla will use.

onAfterModuleList

Description

This event is triggered after Joomla has obtained the list of modules to run, but before the list is cleaned.

You can use this event to alter the modules which Joomla will use.

Event Arguments

The event class \Joomla\CMS\Event\Module\AfterModuleListEvent has the following arguments:

• modules - the array of modules

• subject - null (not used)

Return Value

You can update the set of modules which Joomla will use.

onAfterCleanModuleList

Description

This event is triggered after Joomla has obtained and cleaned the list of modules to run.

You can use this event to alter the modules which Joomla will use.

Event Arguments

The event class \Joomla\CMS\Event\Module\AfterCleanModuleListEvent has the following arguments:

• modules - the array of modules

• subject - null (not used)

Return Value

You can update the set of modules which Joomla will use.

onRenderModule

Description

This event is triggered after Joomla has run each module, and obtained the module raw output.

Event Arguments

The event class \Joomla\CMS\Event\Module\RenderModuleEvent has the following arguments:

• module - the module which has been rendered

(This is actually the 'subject' element in the array returned by $event->getArguments().)

• attributes - the array of attributes. The $attributes array contains the elements:

  • name - name of the template position

  • style - module style

Return Value

You can update the attributes.

Changing the style attribute will change the module style to apply.

Change the name attribute will have no effect.

You can also change the module content directly:

$module->content = "<some html>"

If you set the $module->content to an empty string then Joomla will not attempt to add a module style (chrome wrapper).

onAfterRenderModule

Description

This event is triggered after Joomla has applied the module style (chrome wrapper around the module raw output).

Event Arguments

The event class \Joomla\CMS\Event\Module\AfterRenderModuleEvent has the following arguments:

• module - the module which has been rendered

(This is actually the 'subject' element in the array returned by $event->getArguments().)

• attributes - the array of attributes. The $attributes array contains the elements:

  • name - name of the template position

  • style - module style

Return Value

You can change the module content directly:

$module->content = "<some html>"

onAfterRenderModules

Description

This event is triggered after Joomla has rendered all of the modules for a given template position.

Event Arguments

The event class \Joomla\CMS\Event\Module\AfterRenderModulesEvent has the following arguments:

• content - the HTML content for the module position

• attributes - the array of attributes. The $attributes array contains the elements:

  • name - name of the template position

  • style - the default module style, as specified in the template file

• subject - null (not used)

Return Value

You can update the content.