removing a template from the cache

Question

I'm getting a template via:

<?php echo $this->getChildHtml('ajaxCart'); ?>

and the block is declared like this:

<block type="page/html_topmenu" name="ajaxCart" as="ajaxCart" template="page/html/ajaxCart.phtml"/>

How can I remove this from our caching system?

Answer 1

If you are using the full page cache of Magento Enterprise, you need to do two things:

1. disable block caching for the block
2. exclude the block from otherwise cached pages with full page cache hole punching

1. Disable block caching

Change the block declaration to:

<block type="page/html_topmenu" name="ajaxCart" as="ajaxCart" template="page/html/ajaxCart.phtml">
    <action method="setCacheLifetime"></action>
</block>

This calls setCacheLifetime(null) and thus disables caching for the block.

More info about setCachelifetime() and how to use it in layout XML can be found here: http://fbrnc.net/blog/2015/06/cache-and-layout-xml-tricks

2. Hole punching

create a module with a etc/cache.xml file like this:

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <placeholders>
        <ajax_cart_cache>
            <block>page/html_topmeu</block>
            <name>ajaxCart</name>
            <placeholder>AJAX_CART</placeholder>
            <container>Your_Module_Model_Container_Ajaxcart</container>
            <cache_lifetime></cache_lifetime>
        </ajax_cart_cache>
    </placeholders>
</config>

and the container model like this:

class Your_Module_Model_Container_Ajaxcart extends Enterprise_PageCache_Model_Container_Abstract
{
    protected function _renderBlock()
    {
        $blockClass = $this->_placeholder->getAttribute('block');
        $template = $this->_placeholder->getAttribute('template');

        $block = new $blockClass;
        $block->setTemplate($template);
        return $block->toHtml();
    }
}