django/middleware/gzip.py

   1 import re
   2
   3 from django.utils.text import compress_string
   4 from django.utils.cache import patch_vary_headers
   5
   6 re_accepts_gzip = re.compile(r'\bgzip\b')
   7
   8 class GZipMiddleware(object):
   9     """
  10     This middleware compresses content if the browser allows gzip compression.
  11     It sets the Vary header accordingly, so that caches will base their storage
  12     on the Accept-Encoding header.
  13     """
  14     def process_response(self, request, response):
  15         # It's not worth compressing non-OK or really short responses.
  16         if response.status_code != 200 or len(response.content) < 200:
  17             return response
  18
  19         patch_vary_headers(response, ('Accept-Encoding',))
  20
  21         # Avoid gzipping if we've already got a content-encoding.
  22         if response.has_header('Content-Encoding'):
  23             return response
  24
  25         # Older versions of IE have issues with gzipped pages containing either
  26         # Javascript and PDF.
  27         if "msie" in request.META.get('HTTP_USER_AGENT', '').lower():
  28             ctype = response.get('Content-Type', '').lower()
  29             if "javascript" in ctype or ctype == "application/pdf":
  30                 return response
  31
  32         ae = request.META.get('HTTP_ACCEPT_ENCODING', '')
  33         if not re_accepts_gzip.search(ae):
  34             return response
  35
  36         response.content = compress_string(response.content)
  37         response['Content-Encoding'] = 'gzip'
  38         response['Content-Length'] = str(len(response.content))
  39         return response