Opened 17 years ago
Last modified 17 years ago
#5324 closed
queryset exclude fails across a many-to-many list — at Initial Version
| Reported by: | Owned by: | Adrian Holovaty | |
|---|---|---|---|
| Component: | Core (Other) | Version: | dev |
| Severity: | Keywords: | exclude m2m many-to-many, qs-rf-fixed | |
| Cc: | Triage Stage: | Accepted | |
| Has patch: | no | Needs documentation: | no |
| Needs tests: | no | Patch needs improvement: | no |
| Easy pickings: | no | UI/UX: | no |
Description
If you try to exclude items from a queryset across a m2m link, it fails to give the expected result.
For instance, assuming I have users, some of whom are in group Editors, some in group Sales, and most are not in a group at all.
- from django.contrib.auth.models import User
- user_qs = User.objects.all() # all users
- non_editor_users = user_qs.exclude(groupsname='Editors') # should be all users excluding those in group Editors
The set wrongly returned from (3) is actually the set of users who are in Sales but not in Editors - it fails to include those users who have no group at all.
The reason is the sql clause generated, which is doing
FROM "auth_user"
LEFT OUTER JOIN "auth_user_groups" AS "m2m_auth_user__groups" ON "auth_user"."id" = "m2m_auth_user__groups"."user_id"
INNER JOIN "auth_group" AS "auth_user__groups" ON "m2m_auth_user__groups"."group_id" = "auth_user__groups"."id"
WHERE ((NOT ("auth_user__groups"."name" = %s))) ORDER BY "auth_user"."username" ASC', ['Editors']
A workaround for this was posted some time back in http://groups.google.com/group/django-users/browse_thread/thread/81eb405071037248/2beb073a93fd68b7
I can't find a ticket for it - please excuse me if it's a duplicate. I guess #2091 might be related under the hood.