How to disable the cache for the block in Magento 2?

Question

protected function _construct()
    {
        $this->addData(
            [
                'cache_lifetime' => false,
                'cache_tags' => array('MY_BLOCK'),
            ]
        );
    }

    public function getCacheKeyInfo()
    {
        return [];
    }

does not work. Why? How to disable the cache for block?

Answer 1

Blocks can be set as non-cacheable by setting the cacheable attribute false in layout XML files. For example

<block class="Block\Class" name="blockname" cacheable="false" />

Pages containing such blocks are not cached.

Also check How do disable caching of custom block

Edit: A single cacheable="false" will disable Full Page Caching for the whole page, making the pages sourcing from that layout file extremely slow! Check https://inviqa.com/blog/how-full-page-cache-works-magento-2

Answer 2

It's important to understand why you don't want to cache block. If this is meant to show some session specific information then you should be looking into

• https://devdocs.magento.com/guides/v2.4/extension-dev-guide/cache/page-caching/private-content.html

One non-recommended option could be also custom controller what returns some data over ajax-call (with POST-method so it wouldn't be cached).

(!) cacheable="false" must not be used. Here will follow, WHY not:

A block with cacheable="false" will make the whole page uncached. It is not used for cache hole-punching. Also older M2 docs page use to says this (To create an uncacheable page, mark any block on that page as uncacheable in the layout using cacheable="false").

New docs is saying

• Blocks that can’t be cached should be marked as non-cacheable in the layout. However, be aware that adding a non-cacheable block to a page prevents the full page cache from caching that page.

• https://devdocs.magento.com/guides/v2.4/extension-dev-guide/cache/page-caching/private-content.html

What it does is that Varnish/Fastly modules will be sending due this attribute value always non-cacheable headers.

When we enable cachable="false" and while using Varnish/Fastly then browser side following headers are sent :

X-Magento-Cache-Debug:MISS
X-Magento-Cache-Control:max-age=0, must-revalidate, no-cache, no-store
Age: 0

For that can be debugged the Magento's page caching code on

vendor/magento/module-page-cache/Model/Layout/LayoutPlugin.php::afterGenerateXml
vendor/magento/module-page-cache/Model/Layout/LayoutPlugin.php::afterGetOutput

where first one should send public Cache-Control with TTL and second should send X-Magento-Tags for Varnish/Fastly.

Both are using isCacheable() check where this always returns FALSE due following check (check if in current layout there are any attributes:cacheable="false"):

$cacheableXml = !(bool)count($this->getXml()->xpath('//' . Element::TYPE_BLOCK . '[@cacheable="false"]'));

When we remove cacheable="false" then we start to get isCacheable() checks as TRUE and also get headers correctly on start-/category-/productpages.

X-Magento-Cache-Control:max-age=86400, public, s-maxage=86400
X-Magento-Cache-Debug:HIT
X-Magento-Cache-Hits:1
Age:32

Answer 3

I have made non-cacheable for Pricing block

<?php

namespace Custom\Module\Block\Pricing\Render;

class ExtendFinalPriceBox extends \Magento\Catalog\Pricing\Render\FinalPriceBox {

    public function getCacheLifetime()
    {
        return null;
    }

}

Answer 4

Try to avoid using cacheable="false" as this disables cache for the entire page and causes performance issues.

When using Varnish you can use the ttl attribute instead, like:

<block class="Block\Class" name="blockname" ttl="0" />

Answer 5

I wouldn't recommend using cacheable="false" since it's a "page cache breaker" as it states in Magento developer docs. If you make getCacheLifetime in the block to return null it doesn't stop making ESI requests for the block and ESI requests are not going to get any of the parent page GET context like category ID, etc.

If you remove the block in the layout and re-add with different name it with current dependencies to the block. For example:

<referenceBlock name="catalog.topnav" remove="true" />
<block class="Magento\Theme\Block\Html\Topmenu" name="custom.catalog.topnav" as="catalog.topnav" template="Magento_Theme::html/topmenu.phtml" >
    <!-- Find and put here dependencies that are currently injected to the removed block -->
</block>

This way this block is not loaded by ESI and it doesn't break the page cache.

Answer 6

You can add non-cacheable block only to custom pages. In other case, magento Page Cache will not work for these pages OR update information in block via ajax (magento section requests).