Content Plugin 'loads' multiple times on Category Page

Question

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?

Answer 1

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

If you open the following file:

components\com_content\views\article\view.html.php

you see the event dispatched on line 161:

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

Then in this file:

components\com_content\views\category\view.html.php

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.

Answer 2

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 $body
            JResponse::setBody($body);
   }