Method update_cached_response

cachecontrol/controller.py:471–511

On a 304 we will get a new set of headers that we want to update our cached value with, assuming we have one. This should only ever be called when we've sent an ETag and gotten a 304 as the response.

(
        self, request: PreparedRequest, response: HTTPResponse
    )

                    )

    def update_cached_response(
        self, request: PreparedRequest, response: HTTPResponse
    ) -> HTTPResponse:
        """On a 304 we will get a new set of headers that we want to
        update our cached value with, assuming we have one.

        This should only ever be called when we've sent an ETag and
        gotten a 304 as the response.
        """
        assert request.url is not None
        cache_url = self.cache_url(request.url)
        cached_response = self._load_from_cache(request)

        if not cached_response:
            # we didn't have a cached response
            return response

        # Lets update our headers with the headers from the new request:
        # http://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional-26#section-4.1
        #
        # The server isn't supposed to send headers that would make
        # the cached body invalid. But... just in case, we'll be sure
        # to strip out ones we know that might be problematic due to
        # typical assumptions.
        excluded_headers = ["content-length"]

        cached_response.headers.update(
            {
                k: v
                for k, v in response.headers.items()
                if k.lower() not in excluded_headers
            }
        )

        # we want a 200 b/c we have content via the cache
        cached_response.status = 200

        # update our cache
        self._cache_set(cache_url, request, cached_response)

        return cached_response