Fix creation of deep structures using import in update mode

core/admin/mailu/schemas.py

@@ -909,7 +909,9 @@ class BaseSchema(ma.SQLAlchemyAutoSchema, Storage):
         # stabilize import of auto-increment primary keys (not required),
         # by matching import data to existing items and setting primary key
         if not self._primary in data:
-            for item in getattr(self.recall('parent'), self.recall('field', 'parent')):
+            parent = self.recall('parent')
+            if parent is not None:
+                for item in getattr(parent, self.recall('field', 'parent')):
                     existing = self.dump(item, many=False)
                     this = existing.pop(self._primary)
                     if data == existing:
@@ -919,6 +921,11 @@ class BaseSchema(ma.SQLAlchemyAutoSchema, Storage):
 
         # try to load instance
         instance = self.instance or self.get_instance(data)
+
+        # remember instance as parent for pruning siblings
+        if not self.Meta.sibling and self.context.get('update'):
+            self.store('parent', instance)
+
         if instance is None:
 
             if '__delete__' in data:
@@ -931,9 +938,6 @@ class BaseSchema(ma.SQLAlchemyAutoSchema, Storage):
         else:
 
             if self.context.get('update'):
-                # remember instance as parent for pruning siblings
-                if not self.Meta.sibling:
-                    self.store('parent', instance)
                 # delete instance from session when marked
                 if '__delete__' in data:
                     self.opts.sqla_session.delete(instance)
@@ -1014,8 +1018,10 @@ class BaseSchema(ma.SQLAlchemyAutoSchema, Storage):
                 del_items = True
 
         if add_items or del_items:
+            parent = self.recall('parent')
+            if parent is not None:
                 existing = {item[self._primary] for item in items if self._primary in item}
-            for item in getattr(self.recall('parent'), self.recall('field', 'parent')):
+                for item in getattr(parent, self.recall('field', 'parent')):
                     key = getattr(item, self._primary)
                     if key not in existing:
                         if add_items: