About Cache Invalidation for URL Path
When you have views cached with the @cache_page decorator, after updates, you will want to invalidate the cache. Here is a utility function to do that:
def invalidate_cache_for_url(url_path):
"""Delete the cache_page header key for a given URL path.
Mirrors Django's _generate_cache_header_key so the correct cache entry
is removed without needing a live request object.
"""
import hashlib
from django.core.cache import cache
website_url = getattr(settings, "WEBSITE_URL", "")
if not website_url:
return
full_url = website_url.rstrip("/") + url_path
url_hash = hashlib.md5(
full_url.encode("ascii"),
usedforsecurity=False,
).hexdigest()
key_prefix = getattr(settings, "CACHE_MIDDLEWARE_KEY_PREFIX", "")
cache_key = f"views.decorators.cache.cache_header.{key_prefix}.{url_hash}"
if settings.USE_I18N or settings.USE_L10N:
cache_key += f".{settings.LANGUAGE_CODE}"
if settings.USE_TZ:
cache_key += f".{settings.TIME_ZONE}"
cache.delete(cache_key)
To use this function, run it in the form views or post-save signal handlers:
invalidate_cache_for_url(
reverse("tricks:trick_details", kwargs={"trick_id": instance.pk})
)
invalidate_cache_for_url(
reverse("tricks:trick_list")
)
The function assumes that you have WEBSITE_URL setting pointing to your host in the project settings, e.g.:
WEBSITE_URL = "https://www.djangotricks.com"
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