Fix AttributeError on ListModelVersions in the browser

arkindex/training/api.py

@@ -81,20 +81,22 @@ class ModelVersionsList(ListCreateAPIView):
     permission_classes = (IsVerified, )
     serializer_class = ModelVersionSerializer
 
+    @cached_property
+    def model(self):
+        return get_object_or_404(Model.objects.using('default').all(), id=self.kwargs['pk'])
+
+    @cached_property
+    def access_level(self):
+        return get_max_level(self.request.user, self.model)
+
     def get_queryset(self):
-        self.model = self.get_object()
+        self.check_object_permissions(self.request, self.model)
         qs = self.model.versions.order_by('-created')
         if self.access_level < Role.Contributor.value:
             qs = qs.filter(tag__isnull=False, state=ModelVersionState.Available)
         return qs
 
-    def get_object(self):
-        model = get_object_or_404(Model.objects.using('default').all(), id=self.kwargs['pk'])
-        self.check_object_permissions(self.request, model)
-        return model
-
     def check_object_permissions(self, request, model):
-        self.access_level = get_max_level(self.request.user, model)
         needed_level, error_msg = (
             Role.Guest.value,
             'You need a Guest access to list versions of a model.',
@@ -117,7 +119,7 @@ class ModelVersionsList(ListCreateAPIView):
         return context
 
     def create(self, request, *args, **kwargs):
-        self.model = self.get_object()
+        self.check_object_permissions(self.request, self.model)
         return super().create(request, *args, **kwargs)