I have a plugin where I am trying to instantiate a new class but every time the plugin was enabled, the page kept dying saying the object already exists. Upon investigating, I found out that it only happens in Category Page and not Article page.

So I removed everything in the code and had the following code:

class plgContentFoobar extends JPlugin
  public function onContentPrepare($context, &$row, &$params, $page = 0)
    echo 1;

On the Article page, it just outputs once as expected but on a category page; it outputs 15 times. Is there anything I need to be aware which is causing this on the category pages?

  • How many articles are displayed on the category page?
    – Lodder
    Jun 23, 2016 at 13:10
  • @Lodder 14 articles on that page.
    – sifu
    Jun 23, 2016 at 13:25

2 Answers 2


Right, so the function executes 15 times and you have 14 articles assigned to a category.

If you open the following file:


you see the event dispatched on line 161:

$dispatcher->trigger('onContentPrepare', array ('com_content.article', &$item, &$item->params, $offset));

Then in this file:


You also see it dispatched on line 106:

$dispatcher->trigger('onContentPrepare', array ('com_content.category', &$item, &$item->params, 0));

As you are on the category view and have 14 articles assigned to the category, the onContentPrepare is dispatched 14 times and then once again from the category view.

  • That explains it. Marking it as an answer but is it possible to dispatch the onContentPrepare just once? What I am trying to do requires the code to run just once otherwise it fails which explains why it worked on Article Page and not Category page.
    – sifu
    Jun 23, 2016 at 13:54
  • It would be best to create a new question, showing the full code your using
    – Lodder
    Jun 23, 2016 at 14:05

Contnet plugins fire on each content portion - each module, each article on a blog page and so on. If you want to replace something unsing one run of a plugin you should use a system plugin and onAfterRender

    function onAfterRender() {
            $body = JResponse::getBody();
            // replace what you need in the $body
  • This is the appropriate answer for what I wanted to do but for the question I asked, I will keep the 'Marked Answer' as the one above.
    – sifu
    Jun 28, 2016 at 14:20

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