Django < 1.6 template chunk key checker

cache_checker.py

# standard lib
import hashlib

# django
from django.core.cache import cache
from django.utils.encoding import force_bytes
from django.utils.http import urlquote


def make_template_fragment_key(fragment_name, vary_on=[]):
    '''
    Mimicks Django's internal cache key generation to see if a particular
    object is available in the cache.

    This function will be natively supported in Django 1.6, at which time we will
    abandon this use in favor of the official cache API.
    '''
    # Cast the variable as a list if it's not already
    if not isinstance(vary_on, list):
        vary_on = [vary_on]
    key = ':'.join([urlquote(var) for var in vary_on])
    args = hashlib.md5(force_bytes(key))
    cache_key = 'template.cache.%s.%s' % (fragment_name, args.hexdigest())
    return cache_key


def cache_has_key(fragment_name, vary_on=[]):
    key = make_template_fragment_key(fragment_name, vary_on)
    # get() returns default (False, in this case) if the key is found but expired
    return cache.get(key, False)