Ticket #18597: formset-optimisation.diff

django/forms/models.py

@@ -690 +690 @@
         self.save_as_new = save_as_new
         # is there a better way to get the object descriptor?
         self.rel_name = RelatedObject(self.fk.rel.to, self.model, self.fk).get_accessor_name()
+        filter_queryset = True
         if queryset is None:
-            queryset = self.model._default_manager
-        qs = queryset.filter(**{self.fk.name: self.instance})
+            if (self.instance.pk and
+                self.fk.rel.multiple and not self.fk.rel.is_hidden()):
+                try:
+                    queryset = getattr(instance, self.rel_name).get_query_set()
+                except AttributeError:
+                    # It's possible to get here in model inheritance scenarios
+                    # where `self.model` is a subclass `self.fk.model` and
+                    # thus `self.fk.rel.to` has no reverse descriptor for
+                    # `self.model`. If it's not the the case we let the
+                    # `AttributeError` propagate.
+                    if not issubclass(self.model, self.fk.model):
+                        raise
+                else:
+                    filter_queryset = False # It's already filtered
+            if queryset is None:
+                queryset = self.model._default_manager
+        if filter_queryset:
+            queryset = queryset.filter(**{self.fk.name: self.instance})
         super(BaseInlineFormSet, self).__init__(data, files, prefix=prefix,
-                                                queryset=qs, **kwargs)
+                                                queryset=queryset, **kwargs)
 
     def initial_form_count(self):
         if self.save_as_new: