fix migration history

utils/middleware.py

@@ -1,11 +1,14 @@
-class MultipleProxyMiddleware(object):
+class MultipleProxyMiddleware:
     FORWARDED_FOR_FIELDS = [
         'HTTP_X_FORWARDED_FOR',
         'HTTP_X_FORWARDED_HOST',
         'HTTP_X_FORWARDED_SERVER',
     ]
 
-    def process_request(self, request):
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
         """
         Rewrites the proxy headers so that only the most
         recent proxy is used.
@@ -15,3 +18,6 @@ class MultipleProxyMiddleware(object):
                 if ',' in request.META[field]:
                     parts = request.META[field].split(',')
                     request.META[field] = parts[-1].strip()
+
+        response = self.get_response(request)
+        return response