Custom cache plugin

27. Custom Cache Plugin

When to Use

Specialized caching beyond time-based and tag-based: per-user caching, geolocation-based, A/B testing variants, external cache backends.

Steps

1. Create cache plugin — In src/Plugin/views/cache/MyCustomCache.php

   namespace Drupal\mymodule\Plugin\views\cache;
   
   use Drupal\views\Plugin\views\cache\CachePluginBase;
   use Drupal\views\Attribute\ViewsCache;
   
   #[ViewsCache(
     id: "my_custom_cache",
     title: "Custom Cache",
     help: "Custom caching strategy",
   )]
   class MyCustomCache extends CachePluginBase {
     protected function cacheGet($type) {
       $cid = $this->generateCacheId($type);
       return \Drupal::cache()->get($cid);
     }
   
     protected function cacheSet($type) {
       $cid = $this->generateCacheId($type);
       \Drupal::cache()->set($cid, [
         'result' => $this->view->result,
         'total_rows' => $this->view->total_rows ?? 0,
       ], CacheBackendInterface::CACHE_PERMANENT, $this->getCacheTags());
     }
   }
   

2. Generate cache ID — Create unique key per view state

   protected function generateCacheId($type) {
     $parts = [
       'views',
       $this->view->id(),
       $this->view->current_display,
       $type,
       \Drupal::currentUser()->id(),  // Per-user cache
     ];
     return implode(':', $parts);
   }
   

3. Define cache tags — For tag-based invalidation

   public function getCacheTags() {
     $tags = parent::getCacheTags();
     $tags[] = 'user:' . \Drupal::currentUser()->id();
     return $tags;
   }
   

Decision Points

At this step...	If...	Then...
Cache granularity	Per-user caching	Include user ID in cache ID generation
Invalidation	Tag-based clearing	Override getCacheTags() to return relevant tags
Expiration	Time-based expiration	Use cache expiration timestamp in set()
Storage	Custom backend	Inject custom cache backend via create()

Common Mistakes

• Not invalidating on relevant changes → Set proper cache tags; stale results confuse users
• Too granular cache keys → Per-argument caching can explode cache size; balance specificity vs. storage
• Missing cache context → If results vary by language/theme/etc., include in cache ID
• Caching sensitive data → Ensure per-user caching for views with access-controlled content
• Not implementing cacheFlush() → Cache should clear when view config changes

See Also

• Section 13: Caching Configuration — tag-based and time-based strategies
• Reference: core/modules/views/src/Plugin/views/cache/CachePluginBase.php
• Reference: core/modules/views/src/Plugin/views/cache/Tag.php — tag-based cache example