Magento 1.9 Cache – How to Check if Concrete Type of Cache is Enabled

cachemagento-1.9

For example how to check if "Blocks HTML output" is enabled, strangely I have trouble to find out that information.

I'd like to know that in order to add conditions before saving and loading custom cached content which is parts of the HTML block output and is programmed in the template file because in the inner HTML I had to output dynamic data a couple times, so I am doing custom "hole punching" and the block class is not caching the whole template.

Best Answer

Thats how you get all Cache types with the status

Mage::app()->getCacheInstance()->getTypes()

If you take a look in Mage_Core_Model_Cache you can see the Method canUse() The Description of the Method is:

Check if cache can be used for specific data type

I think it's exactly what you need and the return is true or false. You can call it like this:

Mage::app()->getCacheInstance()->canUse('block_html')

Related Solutions

Dynamic Topmenu with Full Page Caching in Magento

If you remove them entirely from the layout doing something like below in the default tags in your local.xml

<reference name="header">
  <action method="unsetChild"><name>top.links</name></action>
</reference>

or per page like

<remove name="top.links" />

Then create a mini module with one controller method such as

public function indexAction()
{   
    $this->loadLayout();
  $this->renderLayout();
}

add this to your local.xml

<dynamicblocks_index_index>

    <reference name="root">
        <action method="setTemplate"><template>dynamicblocks/index.phtml</template></action>
    </reference>   


</dynamicblocks_index_index>

then in your dynamicblocks/index.phtml

<?php echo $this->getLayout()->getBlock('top.links')->toHtml() ?>

This whole page should just render your toplinks and by loading it from the website through an ajax call it won't get cached.

Cache Blocks Containing Form Key (Dynamic Content)

This is how I solved it eventually, add the following methods to the block in question:

const FORM_KEY_PLACEHOLDER = '{{FORM_KEY}}';

protected function _toHtml()
{
    return $this->_insertFormKeyPlaceholder(parent::_toHtml());
}

protected function _afterToHtml($html)
{
    return $this->_restoreFormKey(parent::_afterToHtml($html));
}

protected function _insertFormKeyPlaceholder($html)
{
    /** @var $session Mage_Core_Model_Session */
    $session = Mage::getSingleton('core/session');
    return str_replace($session->getFormKey(), self::FORM_KEY_PLACEHOLDER, $html);
}

protected function _restoreFormKey($html)
{
    /** @var $session Mage_Core_Model_Session */
    $session = Mage::getSingleton('core/session');
    return str_replace(self::FORM_KEY_PLACEHOLDER, $session->getFormKey(), $html);
}

Explanation:

I replace the form key with a placeholder before the rendered block is cached and replace the placeholder with the current form key again after the block has been loaded from cache.

I use _toHtml to insert the placeholder because the return value of this method is immediately written to the cache.

I use _afterToHtml to restore the form key because this method is called immediately after the content has been loaded from cache (or after it has been saved to the cache if it was not cached yet). This method is guaranteed to be called, regardless of the block cache.

Further thougts

A generic solution does not seem to exist yet, but the method described above works for any dynamic content and if you need it in more than one block or with different content, it should be easy to extract the placeholder logic to a separate model.

For replacing the placeholders you could also use the core_block_abstract_to_html_after event, but unfortunately no event exists right before the rendered block gets cached, so an "observer only" solution is not possible without introducing new events in the core.