def cache_expires_in(self, timedelta=timedelta(0)):
"""Sets the Cache-Control header of the response.
See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9
Args:
timedelta - the time this resource can be cached
"""
self.response.headers["Expires"] = utils.format_http_time(datetime.utcnow() + timedelta)
self.response.headers["Cache-Control"] = "max-age=%d" % utils.total_seconds(timedelta)
logging.info("Setting caches to expire after %s" % timedelta)
def handle_if_modified_since(self, last_modified):
"""Checks if the request has the 'If-Modified-Since' header and compares it to the
last_modified datetime. It also emits the 'Last-Modified' header in all responses.
"""
# emit the last-modified header
self.response.headers["Last-Modified"] = utils.format_http_time(last_modified)
# if we got the 'if-modified-since header', raise a 304 if the last modified time
# is before the last-seen time.
if "If-Modified-Since" in self.request.headers:
ims = self.request.headers["If-Modified-Since"]
if utils.parse_http_time(ims) >= last_modified.replace(microsecond=0):
raise errors.NotModifiedError()
def no_cache(self):
"""Sets the cache headers to no-cache"""
self.response.headers["Cache-Control"] = "no-cache"
self.response.headers["Expires"] = utils.format_http_time(datetime(year=1970, month=1, day=1))
