Tagging¶
Works with:
If your application has many intricate relationships between cached items, which makes it complex to invalidate them by route, cache tagging will be useful. It helps you with invalidating many-to-many relationships between content items.
Cache tagging, or more precisely Tagged Cache Invalidation, a simpler version of Linked Cache Invalidation (LCI), allows you to:
- assign tags to your applications’s responses (e.g.,
articles
,article-42
) - invalidate the responses by tag (e.g., invalidate
all responses that are tagged
article-42
)
Hint
When working with Varnish, it is recommended to use the xkey vmod for efficient invalidation. See Tagging with Varnish and configure the proxy client for purgekeys.
Basic Configuration¶
First configure your proxy for tagging (Varnish, Symfony) and see if you want to adjust anything in the proxy client configuration. Then enable tagging in your application configuration:
fos_http_cache:
tags:
enabled: true
For more information, see tags.
Setting and Invalidating Tags¶
You can tag responses in different ways:
- From PHP code by using the response tagger to set tags and the cache manager to invalidate tags;
- Set tags from twig templates with a function;
- In project configuration or using annotations on controller actions.
You can add tags before the response object exists. The tags are automatically added to the response by a listener. The listener also detects pending tag invalidations and flushes them. As with other invalidation operations, tag invalidation requests are flushed to the caching proxy after the response has been sent.
Tagging and Invalidating from PHP Code¶
To add tags to responses, use the ResponseTagger::addTags
method:
use FOS\HttpCacheBundle\Http\SymfonyResponseTagger;
class NewsController
{
public function articleAction(string $id, SymfonyResponseTagger $responseTagger)
{
$responseTagger->addTags(array('news', 'news-' . $id));
// ...
}
}
New in version 2.3.2: Autowiring support has been added in version 2.3.2. In older versions of
the bundle, you need to inject the service
fos_http_cache.http.symfony_response_tagger
into your controller.
To invalidate tags, use the CacheManager::invalidateTags($tags)
method:
use FOS\HttpCacheBundle\CacheManager;
class NewsController
{
/**
* @var CacheManager
*/
private $cacheManager;
public function editAction(string $id, CacheManager $cacheManager)
{
// ...
$cacheManager->invalidateTags(array('news-' . $id));
// ...
}
}
New in version 2.3.2: Autowiring support has been added in version 2.3.2. In older versions of
the bundle, you need to inject the service fos_http_cache.cache_manager
in your controller.
Tagging from Twig Templates¶
In situations where a page is assembled in the templating layer, it can be more convenient to add tags from inside the template. This works the same way as with the response tagger and can also be mixed with the other methods:
{# template.html.twig #}
{{ fos_httpcache_tag('mytag') }}
{{ fos_httpcache_tag(['tag-one', 'tag-two']) }}
Hint
This twig function never outputs anything into the template but is only called for the side effect of adding the tag to the response header.
Note
Tag invalidation from twig would be a strange architecture and is therefore not supported.
Tagging and Invalidating with Configuration Rules¶
Alternatively, you can configure rules for setting and invalidating tags:
// app/config/config.yml
fos_http_cache:
tags:
rules:
-
match:
path: ^/news/article
tags: [news]
Now if a safe request matches the criteria under match
, the response
will be tagged with news
. When an unsafe request matches, the tag news
will be invalidated.
Tagging and Invalidating with Controller Annotations¶
Add the @Tag
annotations to your controllers to set and invalidate tags:
use FOS\HttpCacheBundle\Configuration\Tag;
class NewsController
{
/**
* @Tag("news", expression="'news-'~id")
*/
public function articleAction($id)
{
// Assume $id equals 123
}
}
If articleAction
handles a safe request, a tag news-123
is set
on the response. If a client tries to update or delete news article 123 with an
unsafe request to articleAction
, such as POST or DELETE, tag news-123
is invalidated.
See the @Tag reference for full details.