def process_request(self, request):
"""
Checks whether the page is already cached and returns the cached
version if available.
"""
if not request.method in ("GET", "HEAD"):
request._cache_update_cache = False
return None # Don't bother checking the cache.
# try and get the cached GET response
cache_key = get_cache_key(request, get_key_prefix(), "GET", cache=self.cache)
if cache_key is None:
request._cache_update_cache = True
return None # No cache information available, need to rebuild.
response = self.cache.get(cache_key, None)
# if it wasn't found and we are looking for a HEAD, try looking just for that
if response is None and request.method == "HEAD":
cache_key = get_cache_key(request, get_key_prefix(), "HEAD", cache=self.cache)
response = self.cache.get(cache_key, None)
if response is None:
request._cache_update_cache = True
return None # No cache information available, need to rebuild.
# hit, return cached response
request._cache_update_cache = False
return response
def __init__(self, cache_timeout=None, cache_anonymous_only=None, **kwargs):
# We need to differentiate between "provided, but using default value",
# and "not provided". If the value is provided using a default, then
# we fall back to system defaults. If it is not provided at all,
# we need to use middleware defaults.
cache_kwargs = {}
try:
self.key_prefix = kwargs["key_prefix"]
if self.key_prefix is not None:
cache_kwargs["KEY_PREFIX"] = self.key_prefix
else:
self.key_prefix = ""
except KeyError:
self.key_prefix = get_key_prefix()
cache_kwargs["KEY_PREFIX"] = self.key_prefix
try:
self.cache_alias = kwargs["cache_alias"]
if self.cache_alias is None:
self.cache_alias = DEFAULT_CACHE_ALIAS
if cache_timeout is not None:
cache_kwargs["TIMEOUT"] = cache_timeout
except KeyError:
self.cache_alias = settings.CACHE_MIDDLEWARE_ALIAS
if cache_timeout is None:
cache_kwargs["TIMEOUT"] = settings.CACHE_MIDDLEWARE_SECONDS
else:
cache_kwargs["TIMEOUT"] = cache_timeout
if cache_anonymous_only is None:
self.cache_anonymous_only = getattr(settings, "CACHE_MIDDLEWARE_ANONYMOUS_ONLY", False)
else:
self.cache_anonymous_only = cache_anonymous_only
self.cache = get_cache(self.cache_alias, **cache_kwargs)
self.cache_timeout = self.cache.default_timeout
def process_response(self, request, response):
"""Sets the cache, if needed."""
if not self._should_update_cache(request, response):
# We don't need to update the cache, just return.
return response
if not response.status_code == 200:
return response
# Try to get the timeout from the "max-age" section of the "Cache-
# Control" header before reverting to using the default cache_timeout
# length.
timeout = get_max_age(response)
if timeout == None:
timeout = self.cache_timeout
elif timeout == 0:
# max-age was set to 0, don't bother caching.
return response
patch_response_headers(response, timeout)
if timeout:
cache_key = learn_cache_key(request, response, timeout, get_key_prefix(), cache=self.cache)
if hasattr(response, "render") and callable(response.render):
response.add_post_render_callback(lambda r: self.cache.set(cache_key, r, timeout))
else:
self.cache.set(cache_key, response, timeout)
return response
