Magento – Enable cache for AJAX block

block-cachecachemagento-2.1magento2

I'm having problems with caching a block in Magento 2. The theme I'm using is getting content from the block via an AJAX call.

Is it possible how to cache such block in M2?

Thank you,
Mateusz

Best Answer

Every block in magento2 is by default cacheable. You can disable cacheing of that block by explicitly adding cacheable="false" as the block attribute. Can you make sure that this attribute is not added anywhere for this particular block

Related Solutions

Magento – Exclude one phtml file from cache

For that you need to set the Caching lifetime of the black behind it to zero. Inchoo did an article about this I used a long while back.

Basically you need to the following to the block

protected function _construct()
{
   $this->addData(array(
      'cache_lifetime' => 3600,
      'cache_tags'     => array(Mage_Catalog_Model_Product::CACHE_TAG),
      'cache_key'      => $this->getProduct()->getId(),
   ));
}

But please, read the article, it'll help you

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.