Applying cache tags for entity-based renderingfor Drupal 8 , 9 , 10 , and 11

In our previous lesson, we focused on loading only required fields using entity_load(), a crucial step for reducing data processing. Today, we will build upon that by discussing how to effectively use cache tags for entity-based rendering in Drupal. Leveraging cache tags enables seamless updates and efficient caching strategies, optimizing performance without sacrificing content freshness.

Understanding Cache Tags in Drupal

Cache tags are identifiers attached to cacheable items, crucial for managing dependencies between cached content and Drupal entities. They ensure that when an entity is updated, only relevant cached items are invalidated, preserving cache efficiency while maintaining up-to-date content.

Benefits of Cache Tags

• Targeted Invalidation: Only the cache related to modified content is cleared, maintaining system performance by not over-clearing.
• Scalability: Facilitates efficient cache management as your site and user base grow, without overwhelming the server.
• Consistency: Ensures users see the most current data, boosting reliability and user trust.

Implementing Cache Tags for Entity-Based Rendering

Applying cache tags involves associating them with your rendered output so that pertinent cache entries are invalidated when entity data changes.

Step-by-Step Guide to Applying Cache Tags:

Step 1: Add Cache Tags to Render Arrays

When building render arrays in custom modules or themes, include relevant cache tags. This ensures the cached output adheres to particular entities' state.

// Example: Adding cache tags to a render array.
$build = [
  '#markup' => $node->label(),
  '#cache' => [
    'tags' => $node->getCacheTags(),
  ],
];

Step 2: Use Entity cache tags in Cacheable Metadata

Utilize CacheableMetadata to manage cache contexts and tags, leveraging it for more complex rendering logic or components.

use Drupal\Core\Cache\CacheableMetadata;

function mymodule_render_node($node) {
  $rendered_node = render($node);

  // Apply cache metadata to the rendered node.
  $cache_metadata = CacheableMetadata::createFromRenderArray($rendered_node);
  $cache_metadata->addCacheTags($node->getCacheTags());
  $cache_metadata->applyTo($rendered_node);

  return $rendered_node;
}

Best Practices for Cache Tags:

• Granular Tags: Use specific tags related to the content type or entity to minimize unnecessary cache clear events.
• Tag Combinations: Use combinations for complex rendering scenarios to ensure all necessary dependencies are accounted for.
• Testing: Validate that cache invalidation works as intended, ensuring that changes are reflected without undue performance hits.

Conclusion

By applying cache tags for entity-based rendering, you fine-tune Drupal’s caching capabilities, improving both performance and the reliability of content delivery. This technique enables you to manage large sites efficiently, ensuring a smooth and rapid user experience, even as content frequently updates.

What's Next?

Our next lesson will introduce "Limiting Field Formatters for Performance," where we'll dive into optimizing field processing by controlling formatter usage. This will further streamline your Drupal site's performance. Join us as we continue simplifying and refining your content delivery process!