Re: [Django] #12807: Empty results break when part of ORs

[Django]

#12807: Empty results break when part of ORs
-------------------------------------+-------------------------------------
Reporter: sciyoshi | Owner: nobody
Type: Bug | Status: new
Milestone: | Component: Database layer
Version: 1.1 | (models, ORM)
Resolution: | Severity: Normal
Triage Stage: Accepted | Keywords: query, sql, q,
Needs documentation: 0 | filter, or, empty
Patch needs improvement: 1 | Has patch: 1
| Needs tests: 0
| Easy pickings: 0
-------------------------------------+-------------------------------------
Changes (by patchhammer):

* needs_better_patch: 0 => 1
* easy: => 0

Comment:

12807.patch fails to apply cleanly on to trunk

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Ticket URL: <http://code.djangoproject.com/ticket/12807#comment:5>
Django <https://code.djangoproject.com/>
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[Django]

#12807: Empty results break when part of ORs
-------------------------------------+-------------------------------------
Reporter: sciyoshi | Owner: nobody
Type: Bug | Status: new

Component: Database layer | Version: 1.1
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: query, sql, q, | Needs documentation: 0
filter, or, empty | Patch needs improvement: 1

Has patch: 1 | UI/UX: 0

Needs tests: 0 |
Easy pickings: 0 |
-------------------------------------+-------------------------------------

Description changed by akaariai:

Old description:

> The following query:
>
> User.objects.filter((Q(pk=3) | ~Q(pk__in=[]) & Q(pk=1))
>
> currently breaks, since ~Q(pk__in=[]) isn't noticed as being full, thus
> leading to the following query:
>
> >>> User.objects.filter((Q(pk=3) | ~Q(pk__in=[])) &
> Q(pk=1)).values('id').query.as_sql()
> ('SELECT "auth_user"."id" FROM "auth_user" WHERE (("auth_user"."id" =
> %s ) AND "auth_user"."id" = %s )', (3, 1))
>
> and giving an empty result set, instead of the correct
>
> >>> User.objects.filter((Q(pk=3) | ~Q(pk__in=[])) &
> Q(pk=1)).values('id').query.as_sql()
> ('SELECT "auth_user"."id" FROM "auth_user" WHERE ("auth_user"."id" =
> %s )', (1,))
>
> which returns the single user with PK 1.
>
> Attaching a patch which fixes it by making as_sql() raise FullResultSet
> and adds a test case. The issue could also be fixed by checking if the
> child's as_sql() is empty, but this seemed cleaner.

New description:

The following query:

`User.objects.filter((Q(pk=3) | ~Q(pk__in=[]) & Q(pk=1))`

currently breaks, since `~Q(pk__in=[])` isn't noticed as being full, thus
leading to the following query:

>>> `User.objects.filter((Q(pk=3) | ~Q(pk__in=[])) &
Q(pk=1)).values('id').query.as_sql()`
('SELECT "auth_user"."id" FROM "auth_user" WHERE (("auth_user"."id" =
%s ) AND "auth_user"."id" = %s )', (3, 1))

and giving an empty result set, instead of the correct

>>> `User.objects.filter((Q(pk=3) | ~Q(pk__in=[])) &
Q(pk=1)).values('id').query.as_sql()`
('SELECT "auth_user"."id" FROM "auth_user" WHERE ("auth_user"."id" =
%s )', (1,))

which returns the single user with PK 1.

Attaching a patch which fixes it by making as_sql() raise FullResultSet
and adds a test case. The issue could also be fixed by checking if the
child's as_sql() is empty, but this seemed cleaner.

--

--
Ticket URL: <https://code.djangoproject.com/ticket/12807#comment:7>

[Django]

#12807: Empty results break when part of ORs
-------------------------------------+-------------------------------------
Reporter: sciyoshi | Owner: nobody

Type: Bug | Status: closed

Component: Database layer | Version: 1.1

(models, ORM) | Resolution: fixed

Severity: Normal | Triage Stage: Accepted
Keywords: query, sql, q, | Needs documentation: 0
filter, or, empty | Patch needs improvement: 1
Has patch: 1 | UI/UX: 0
Needs tests: 0 |
Easy pickings: 0 |
-------------------------------------+-------------------------------------

Changes (by Anssi Kääriäinen <akaariai@…>):

* status: new => closed
* resolution: => fixed

Comment:

In [changeset:"58c6d0209d71872f0682d478921db1e00496e16c"]:
{{{
#!CommitTicketReference repository=""
revision="58c6d0209d71872f0682d478921db1e00496e16c"
Fixed #12807 -- EmptyResultSet ORed condition

The EmptyResultSet wasn't treated correctly so the end results was
incorrect, too. The bug had been already fixed in master so only tests
added.
}}}

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Ticket URL: <https://code.djangoproject.com/ticket/12807#comment:8>