django1/django/middleware/gzip.py

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import re
from django.utils.text import compress_string
from django.utils.cache import patch_vary_headers
re_accepts_gzip = re.compile(r'\bgzip\b')
class GZipMiddleware(object):
"""
This middleware compresses content if the browser allows gzip compression.
It sets the Vary header accordingly, so that caches will base their storage
on the Accept-Encoding header.
"""
def process_response(self, request, response):
# It's not worth attempting to compress really short responses.
if len(response.content) < 200:
return response
patch_vary_headers(response, ('Accept-Encoding',))
# Avoid gzipping if we've already got a content-encoding.
if response.has_header('Content-Encoding'):
return response
# MSIE have issues with gzipped response of various content types.
if "msie" in request.META.get('HTTP_USER_AGENT', '').lower():
ctype = response.get('Content-Type', '').lower()
if not ctype.startswith("text/") or "javascript" in ctype:
return response
ae = request.META.get('HTTP_ACCEPT_ENCODING', '')
if not re_accepts_gzip.search(ae):
return response
# Return the compressed content only if it's actually shorter.
compressed_content = compress_string(response.content)
if len(compressed_content) >= len(response.content):
return response
if response.has_header('ETag'):
response['ETag'] = re.sub('"$', ';gzip"', response['ETag'])
response.content = compressed_content
response['Content-Encoding'] = 'gzip'
response['Content-Length'] = str(len(response.content))
return response