How to manually clear/update a cached view in django

Question

My goal is to cache a view until an event occurs where the view's cache would need to expire, otherwise cache for 1 hour. This is what I have in urls.py

url(r'^get_some_stuff/$', cache_page(60 * 60, key_prefix='get_some_stuff')(views.StuffView.as_view())),

And this works fine. Now I'm trying to fetch the cached view to verify that there's something there and I tried this:

from django.core.cache import cache
cache.get('get_some_stuff')

But this returns None. I was hoping to do something like this:

from django.core.cache import cache
#relevant event happened
cache.delete('get_some_stuff')

What's the right way to handle cache?

I've tried passing the uri path:

cache.get('/api/get_some_stuff/')

And I still get None returned.

>>> cache.has_key('/api/get_some_stuff/')
False
>>> cache.has_key('/api/get_some_stuff')
False
>>> cache.has_key('get_some_stuff')
False

I've reviewed the suggested answer and it does not solve the underlying issue at all. It does not appear to be as trivial as passing the uri routing path as the key since keys are somewhat abstracted within django.

Possible duplicate of [Clearing specific cache in Django](https://stackoverflow.com/questions/8784400/clearing-specific-cache-in-django) — Brown Bear, Oct 31 '17 at 16:50
@BearBrown I've also tried passing the URI to cache.get and nothing — Stupid.Fat.Cat, Oct 31 '17 at 16:59

score 2 · Answer 1 · answered Mar 23 '21 at 22:08

Here is a code snippet from Relekang about expire @cache_page

from django.core.cache import cache
from django.core.urlresolvers import reverse
from django.http import HttpRequest
from django.utils.cache import get_cache_key

def expire_page_cache(view, args=None):
    """
    Removes cache created by cache_page functionality. 
    Parameters are used as they are in reverse()
    """

    if args is None:
        path = reverse(view)
    else:
        path = reverse(view, args=args)

    request = HttpRequest()
    request.path = path
    key = get_cache_key(request)
    if cache.has_key(key):
        cache.delete(key)

it seems request should be view request, not HttpRequest(). – Akhil S Jun 15 '21 at 18:15 — Akhil S, Jun 15 '21 at 18:15

score 1 · Answer 2 · answered Oct 31 '17 at 20:34

Django's Cache framework only allows to cache data for predefined time and to clear expired cache data you may need to use django-signals to notify some receiver function which clears cache.

And cache.get, cache.has_key, cache.delete requires complete cache_key to be passed not the url or key-prefix. As django takes care of the keys we don't have much control to get or delete data.

If you are using database caching then use raw sql query to delete cache record from the database table when it's stale. write a query which says delete from cache_table with cache_key like ('%1:views.decorators.cache.cache_page%')

I faced same issues with per-view caching and I went with low-level cache api. I cached final result querysets using cache.set() and good part is you can set your own key and play with it.

How to manually clear/update a cached view in django

2 Answers2