Reorder initializing the view

Determining the version and performing content negotiation should be done before ensuring the permission of the request. The reason is that these information can be used in handling the exceptions. For example different versions may return different error scheme. Also, the rendering class can be used to determine how to exception handler response should be rendered.

rest_framework/views.py

@@ -372,11 +372,6 @@ class APIView(View):
         """
         self.format_kwarg = self.get_format_suffix(**kwargs)
 
-        # Ensure that the incoming request is permitted
-        self.perform_authentication(request)
-        self.check_permissions(request)
-        self.check_throttles(request)
-
         # Perform content negotiation and store the accepted info on the request
         neg = self.perform_content_negotiation(request)
         request.accepted_renderer, request.accepted_media_type = neg
@@ -385,6 +380,11 @@ class APIView(View):
         version, scheme = self.determine_version(request, *args, **kwargs)
         request.version, request.versioning_scheme = version, scheme
 
+        # Ensure that the incoming request is permitted
+        self.perform_authentication(request)
+        self.check_permissions(request)
+        self.check_throttles(request)
+
     def finalize_response(self, request, response, *args, **kwargs):
         """
         Returns the final response object.