Hooks

Hooks offer plug-ins the possibility to intervene in the execution logic of the online shop at predefined points and to manipulate transferred data or the output document, if necessary.
This is possible anywhere in the code of the online shop where the function executeHook(int $nHook, array $args_arr) is explicitly executed.

A list of all available hooks can be found in section “List of all hooks”.
You can learn how to specify to the online shop which hooks your plug-in wants to use in info.xml under section “Plug-in hooks”.

Example:

Execute a hook before storing a news comment in the database:

executeHook(\HOOK_NEWS_PAGE_NEWSKOMMENTAR_EINTRAGEN, ['comment' => &$oNewsKommentar]);

Plug-ins registered on this hook can use the array $args_arr in the relevant hook file and modify it, if necessary.

For example, if a plug-in uses the above-mentioned hook HOOK_NEWS_PAGE_NEWSKOMMENTAR_EINTRAGEN (ID 34), the comment transferred there can be modified.

<?php

if (!empty($args_arr['comment'])) {
    $args_arr['comment'] .= '<br>This text is attached to non-empty comments!';
}

As of JTL-Shop 5.x, there is a new alternative to the familiar hooks in JTL-Shop - the EventDispatcher.
For more information on how to make use of this new feature, see the “Bootstrapping” section under “The EventDispatcher”.

DOM manipulation

One of the most common application cases is to write your own HTML code into the output document.
The hook HOOK_SMARTY_OUTPUTFILTER (ID 140) is used for this purpose. There, any content can be inserted into the DOM via PHPQuery.
As a simple example, a plug-in could render the contents of a template via Smarty and append it to the body of the HTML document:

<?php

$template = $oPlugin->cFrontendPfad . 'templates/' . 'example.tpl';
pq('body')->append($smarty->fetch($template));

You can find a general overview about PHPQuery at Documentation.