#28333: Filter and subquery for window expressions
-------------------------------------+-------------------------------------
Reporter: Mads Jensen | Owner: Simon
| Charette
Type: New feature | Status: assigned
Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution:
Keywords: window orm filter | Triage Stage: Accepted
subquery GSoC |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by master):
My code was working till 3.2, but with
https://code.djangoproject.com/changeset/8c3046daade8d9b019928f96e53629b03060fe73,
it doesn't anymore.
Here is a simplified (no filter(), less annotate(), fake Value(), ...)
demonstrator:
{{{
>>> from postman.models import Message
>>> qs1=Message.objects.values_list('id').order_by()
>>> print(qs1.query) # correct
SELECT "postman_message"."id" FROM "postman_message"
>>> qs2=Message.objects.values('thread').annotate(id=Value(2,
IntegerField())).values_list('id').order_by()
>>> print(qs2.query) # correct
SELECT 2 AS "id" FROM "postman_message"
>>> print(qs1.union(qs2).query) # will cause my problem
SELECT "postman_message"."id" AS "col1" FROM "postman_message" UNION
SELECT 2 AS "id" FROM "postman_message"
}}}
The noticeable point is the introduction of the alias `AS "col1"`, not
compatible with the `id` in the second part.
In the full code, the union is injected in another query, of the form
`SELECT ... FROM ... INNER JOIN (the union) PM ON (... = PM.id)`
So it leads to the error: `django.db.utils.OperationalError: no such
column: PM.id`
In db/models/sql/compiler.py, get_combinator_sql(), the call is imposed
as: `as_sql(with_col_aliases=True)`
I don't know how to solve this problem.
Any advice?
--
Ticket URL: <https://code.djangoproject.com/ticket/28333#comment:35>
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