Class UpdateCacheMiddleware

django/middleware/cache.py:61–143

Response-phase cache middleware that updates the cache if the response is cacheable. Must be used as part of the two-part update/fetch cache middleware. UpdateCacheMiddleware must be the first piece of middleware in MIDDLEWARE so that it'll get called last during the response p

class UpdateCacheMiddleware(MiddlewareMixin):
    """
    Response-phase cache middleware that updates the cache if the response is
    cacheable.

    Must be used as part of the two-part update/fetch cache middleware.
    UpdateCacheMiddleware must be the first piece of middleware in MIDDLEWARE
    so that it'll get called last during the response phase.
    """

    def __init__(self, get_response):
        super().__init__(get_response)
        self.cache_timeout = settings.CACHE_MIDDLEWARE_SECONDS
        self.page_timeout = None
        self.key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
        self.cache_alias = settings.CACHE_MIDDLEWARE_ALIAS

    @property
    def cache(self):
        return caches[self.cache_alias]

    def _should_update_cache(self, request, response):
        return hasattr(request, "_cache_update_cache") and request._cache_update_cache

    def process_response(self, request, response):
        """Set 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 response.streaming or response.status_code not in (200, 304):
            return response

        # Don't cache responses that set a user-specific (and maybe security
        # sensitive) cookie in response to a cookie-less request.
        if (
            not request.COOKIES
            and response.cookies
            and has_vary_header(response, "Cookie")
        ):
            return response

        # Don't cache responses when the Cache-Control header is set to
        # private, no-cache, or no-store.
        cache_control = response.get("Cache-Control", ())
        if any(
            directive in cache_control
            for directive in (
                "private",
                "no-cache",
                "no-store",
            )
        ):
            return response

        # Don't cache responses when the Vary header contains '*'.
        if has_vary_header(response, "*"):
            return response