42 lines
2.1 KiB
Python
42 lines
2.1 KiB
Python
from django.utils.http import http_date, parse_http_date_safe
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class ConditionalGetMiddleware(object):
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"""
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Handles conditional GET operations. If the response has an ETag or
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Last-Modified header, and the request has If-None-Match or
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If-Modified-Since, the response is replaced by an HttpNotModified.
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Also sets the Date and Content-Length response-headers.
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"""
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def process_response(self, request, response):
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response['Date'] = http_date()
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if not response.streaming and not response.has_header('Content-Length'):
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response['Content-Length'] = str(len(response.content))
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# If-None-Match must be ignored if original result would be anything
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# other than a 2XX or 304 status. 304 status would result in no change.
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# http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.26
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if 200 <= response.status_code < 300 and response.has_header('ETag'):
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if_none_match = request.META.get('HTTP_IF_NONE_MATCH')
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if if_none_match == response['ETag']:
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# Setting the status is enough here. The response handling path
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# automatically removes content for this status code (in
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# http.conditional_content_removal()).
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response.status_code = 304
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# If-Modified-Since must be ignored if the original result was not a 200.
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# http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.25
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if response.status_code == 200 and response.has_header('Last-Modified'):
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if_modified_since = request.META.get('HTTP_IF_MODIFIED_SINCE')
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if if_modified_since is not None:
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if_modified_since = parse_http_date_safe(if_modified_since)
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if if_modified_since is not None:
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last_modified = parse_http_date_safe(response['Last-Modified'])
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if last_modified is not None and last_modified <= if_modified_since:
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# Setting the status code is enough here (same reasons as
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# above).
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response.status_code = 304
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return response
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