CODEWITHSUNDEEP
pythondjangocaching
Rafael Capucho
Rafael Capucho

Reputation: 461

Can't delete cache for specific entry in Django

I'm trying to purge cache for one specific Entry when it is saved using signals.

I'm using decorators (signals and render_to) from django-annoying

@signals.post_save(sender=Artigo)
def artigo_post_save(instance, **kwargs):

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

    # cache.delete(instance.get_absolute_url()) # not work

    request = HttpRequest()
    request.method = "GET"
    request.path = '/' + instance.get_absolute_url()

    print 'request path: ', request.path

    key = get_cache_key(request=request, 
                        key_prefix=settings.CACHE_MIDDLEWARE_KEY_PREFIX)

    print "found key" if cache.has_key(key) else "notfound key"

    if cache.has_key(key):
        cache.delete(key)
        cache.set(key, None, 0)

Some settings:

SESSION_ENGINE = "django.contrib.sessions.backends.cache"
CACHE_MIDDLEWARE_ANONYMOUS_ONLY = True
CACHE_MIDDLEWARE_KEY_PREFIX = 'cache'
CACHE_MIDDLEWARE_SECONDS = 600

CACHES = {
    'default': {
            'LOCATION': '',
            'BACKEND': 'django.core.cache.backends.locmem.LocMemCache'
     },
}

And the view:

@cache_page(60 * 60)
@render_to('artigo.html')
def artigo(request, categoria_slug, extra_slug="", artigo_slug=""):
    ...

Thank you.

EDIT:
I did Ilvar changes and now i'm getting "found key" as return but I still can't delete cache:

    key = _generate_cache_header_key(key_prefix=settings.CACHE_MIDDLEWARE_KEY_PREFIX, request=request)
    key = key.replace(settings.LANGUAGE_CODE, settings.LANGUAGES[0][0])

Conf:

LANGUAGE_CODE = 'pt-BR'

LANGUAGES = (
        ('pt-BR','Portugues'),
)

Upvotes: 14

Views: 4084

Answers (1)

xeor
xeor

Reputation: 5455

cache.set(key, None, 0) should be enough, I've been clearing cache keys that way before.

If you are able to, can you try the cache.clear(), to clear it all? Just to see if it works.

Are non of your cache keys deletable? Is the output of this as expected?

cache.set('testkey', 'testvalue', 600)
cache.get('testkey')
cache.delete('testkey')
cache.get('testkey')
cache.set('testkey', 'testvalue2', 600)
cache.set('testkey', 'another value', 600)
cache.get('testkey')

And have you tried with another caching backend? It looks like everything you are doing is correct.

Maybe the error is in the backend, some configuration that wont let it overwrite keys or something weird..

Upvotes: 3

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