| 1234567891011121314151617181920212223242526272829303132333435363738394041 |
- from django.utils.cache import (
- cc_delim_re, get_conditional_response, set_response_etag,
- )
- from django.utils.deprecation import MiddlewareMixin
- from django.utils.http import parse_http_date_safe
-
-
- class ConditionalGetMiddleware(MiddlewareMixin):
- """
- Handle conditional GET operations. If the response has an ETag or
- Last-Modified header and the request has If-None-Match or If-Modified-Since,
- replace the response with HttpNotModified. Add an ETag header if needed.
- """
- def process_response(self, request, response):
- # It's too late to prevent an unsafe request with a 412 response, and
- # for a HEAD request, the response body is always empty so computing
- # an accurate ETag isn't possible.
- if request.method != 'GET':
- return response
-
- if self.needs_etag(response) and not response.has_header('ETag'):
- set_response_etag(response)
-
- etag = response.get('ETag')
- last_modified = response.get('Last-Modified')
- last_modified = last_modified and parse_http_date_safe(last_modified)
-
- if etag or last_modified:
- return get_conditional_response(
- request,
- etag=etag,
- last_modified=last_modified,
- response=response,
- )
-
- return response
-
- def needs_etag(self, response):
- """Return True if an ETag header should be added to response."""
- cache_control_headers = cc_delim_re.split(response.get('Cache-Control', ''))
- return all(header.lower() != 'no-store' for header in cache_control_headers)
|
