On the Joomla “onContentBeforeSave” and “onContentAfterSave” Events

If you’re into Joomla plugin development, then you are most likely familiar with the onContentBeforeSave and the onContentAfterSave events. The first event is triggered just before someone saves any Joomla content item, and the second event is triggered (you’ve guessed it) just after someone saves a Joomla content item.

The onContentBeforeSave event is typically used to alter the data that is about to be saved to the database, or to do something just before the data is saved.

The onContentAfterSave event is typically used to do something after the data is saved, for example, redirect to a specific page, or perform one or more database activities.

Now, if you read the first paragraph very carefully, you will understand that there is a problem. Since these events are run when any content item is saved, then this means that they can run at the wrong time. For example, if you have code that should be run when an article is saved, then this code will also run when you save other content items (such as categories or content items of non-core extensions)… In the absolute majority of cases, this is not a desirable behavior. So, in order to avoid this problem, developers add a condition in the beginning of the event to tell it which context it should run in. For example, if a developer wants to have the onContentBeforeSave run only when an article is saved, then he adds the following line to the beginning of the onContentBeforeSave function:

if ($context !== 'com_content.form') return true;

The above line ensures that the event runs only when an article is being saved.

What the absolute majority of Joomla developers don’t know is that there is another, more elegant solution to the problem, and it is by assigning different names to the above events based on the content type. The Joomla core already takes advantage of this hidden functionality: let us take a look at the model of the plugin extension, which is the file plugin.php which is located under the administrator/components/com_plugins/models. In particular, let us look at the constructor of that model:

public function __construct($config = array())
{
	$config = array_merge(
		array(
			'event_after_save'  => 'onExtensionAfterSave',
			'event_before_save' => 'onExtensionBeforeSave',
			'events_map'        => array(
				'save' => 'extension'
			)
		), $config
	);

	parent::__construct($config);
}

You can see that the event_before_save and the event_after_save configuration parameters were set to onExtensionBeforeSave and onExtensionAfterSave respectively. By default, these 2 configuration parameters are set to onContentBeforeSave and onContentAfterSave (this default is set in the admin.php file which is located under the libraries/legacy/model folder). So, when a Joomla plugin is saved, it triggers the onExtensionBeforeSave and onExtensionAfterSave events instead of the onContentBeforeSave and onContentAfterSave events. What does this mean? Well, it means that you can avoid triggering the default before save and the after save events by explicitly setting the values of the event_before_save and the event_after_save configuration parameters in your extension’s model.

We haven’t really discovered fire in this post, but we have demonstrated one best practice in the implementation of Joomla extensions, a best practice that we believe can benefit some Joomla developers out there by saving them some headache.

Now if you, our dear reader, need help with your Joomla events or with the development of Joomla extensions, then please contact us. We are experts in Joomla coding, our work is super clean, and our fees are really affordable!