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