Disable full page caching for specific block - magento

Question

I'm working with magento EE that has full page caching feature. There is a block that is updated dynamically, but I can't seem to disable its caching.
What I want to achieve ideally: disable caching only for particular block so it would be rendered again each time the page loads.
Things I tried:
Include unsetData to layout file
<action method="unsetData"><key>cache_lifetime</key></action>
<action method="unsetData"><key>cache_tags</key></action>
Set function _saveCache to return false
protected function _saveCache($data, $id, $tags = array(), $lifetime = null) {
return false;
}
Set different values for cache_lifetime
public function __construct()
{
$this->addData(array(
‘cache_lifetime’ => 0,
‘cache_tags’ => array(Mage_Catalog_Model_Product::CACHE_TAG),
));
}
Perhaps I'm missing something in full page caching mechanics?

Answer 1

Well, I found a couple of good posts and implement my caching with etc/cache.xml, that wraps my block with container object.
My cache.xml:
<?xml version="1.0" encoding="UTF-8"?>
<config>
<placeholders>
<namespace_block_unique_node>
<block>module/block_class</block>
<name>name_of_block_in_my_layout</name>
<template>path/to/my/template</template>
<placeholder>UNIQUE_PLACEHOLDER_HERE</placeholder>
<container>Namespace_Module_Model_Caching_Container_BlockName</container>
<cache_lifetime>86400</cache_lifetime>
</namespace_block_unique_node>
</placeholders>
</config>
I used here as block the block that should not be cached, as name name of block in my layout, and as container I've choose my container.
Code for container:
<?php
class Namespace_Module_Model_Caching_Container_BlockName extends Enterprise_PageCache_Model_Container_Abstract
{
protected function _getCacheId()
{
return 'NAMESPACE_MODULE_BLOCKNAME' . $this->_getIdentifier();
}
protected function _getIdentifier()
{
return microtime();
}
protected function _renderBlock()
{
$blockClass = $this->_placeholder->getAttribute('block');
$template = $this->_placeholder->getAttribute('template');
$block = new $blockClass;
$block->setTemplate($template);
$layout = Mage::app()->getLayout();
$block->setLayout($layout);
return $block->toHtml();
}
protected function _saveCache($data, $id, $tags = array(), $lifetime = null) { return false;}
}
Here I putmicrotime() function to identify block, but inside my module I used cookie variables related to my module. I believe that saves redundant reloading of a block when nothing was really changed.
The thing that I didn't found in other tutorials is that I had to create layout variable and assign it to my block, otherwise I was getting only my block instead of whole page.

Answer 2

Here is the solution for disabling FPC for a specific controller (could be extended to specific action as well).
First create an Observer to listen on the controller_action_predispatch event:
public function processPreDispatch(Varien_Event_Observer $observer)
{
$action = $observer->getEvent()->getControllerAction();
// Check to see if $action is a Product controller
if ($action instanceof Mage_Catalog_ProductController)
{
$request = $action->getRequest();
$cache = Mage::app()->getCacheInstance();
// Tell Magento to 'ban' the use of FPC for this request
$cache->banUse('full_page');
}
}
Then add the following to your config.xml file for the module. This goes in the section:
<events>
<controller_action_predispatch>
<observers>
<YOUR_UNIQUE_IDENTIFIER>
<class>YOURMODULE/observer</class>
<method>processPreDispatch</method>
</YOUR_UNIQUE_IDENTIFIER>
</observers>
</controller_action_predispatch>
</events>
Now Magento will serve up your page every time and bypass FPC for the request.
And You can also refer: http://mikebywaters.wordpress.com/2011/12/14/disable-magento-full-page-cache-on-a-per-controller-basis/

Answer 3

cache_lifetime must be set to null to disable cache for this block
public function __construct()
{
$this->addData(array(
‘cache_lifetime’ => null,
));
}