common.py 文件源码

def process_response(self, request, response):
        """
        Calculate the ETag, if needed.

        When the status code of the response is 404, it may redirect to a path
        with an appended slash if should_redirect_with_slash() returns True.
        """
        # If the given URL is "Not Found", then check if we should redirect to
        # a path with a slash appended.
        if response.status_code == 404:
            if self.should_redirect_with_slash(request):
                return self.response_redirect_class(self.get_full_path_with_slash(request))

        if settings.USE_ETAGS and self.needs_etag(response):
            warnings.warn(
                "The USE_ETAGS setting is deprecated in favor of "
                "ConditionalGetMiddleware which sets the ETag regardless of "
                "the setting. CommonMiddleware won't do ETag processing in "
                "Django 2.1.",
                RemovedInDjango21Warning
            )
            if not response.has_header('ETag'):
                set_response_etag(response)

            if response.has_header('ETag'):
                return get_conditional_response(
                    request,
                    etag=response['ETag'],
                    response=response,
                )
        # Add the Content-Length header to non-streaming responses if not
        # already set.
        if not response.streaming and not response.has_header('Content-Length'):
            response['Content-Length'] = str(len(response.content))

        return response