Some related objects that should not be deleted

.gitignore

@@ -8,3 +8,4 @@ MANIFEST
 *.egg
 docs/_build/
 htmlcov/
+.idea/

pinax/models/models.py

@@ -23,12 +23,32 @@ def active(self):
     def delete(self):
         # Fetch related models
         to_delete = get_related_objects(self)
+        # Couldn't find a better way to test if itertools.chain is empty
+        something_to_delete = False
 
         for obj in to_delete:
-            obj.delete()
+            something_to_delete = True
+            field_nullable = False
+            for field in obj._meta.fields:
+                internal_type = field.get_internal_type()
+                if internal_type == "ForeignKey" or internal_type == "OneToOneField":
+                    if field.rel.to == self.__class__ and field.null:
+                        # Set the foreignkey to None
+                        setattr(obj, field.attname, None)
+                        obj.save()
+                        field_nullable = True
+                        # Jump to the next iteration
+                        continue
+
+            if not field_nullable:
+                # Only soft delete the object if there is no foreignkey field
+                # with null=True
+                obj.delete()
+                self.date_removed = timezone.now()
+
+        if not something_to_delete:
+            self.date_removed = timezone.now()
 
-        # Soft delete the object
-        self.date_removed = timezone.now()
         self.save()
 
     class Meta: