#30099: Filter by Count annotated inside Subquery
-------------------------------------+-------------------------------------
Reporter: MrFus10n | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 2.1
(models, ORM) |
Severity: Normal | Resolution:
Keywords: Subquery annotate | Triage Stage:
Count filter | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by MrFus10n:
Old description:
> I want to get authors and annotate minimal count of books in category if
> it is greater than three.
>
> Book and Author models and are not connected with ForeignKey fields (this
> is abstract and simplified, there is a reason):
>
> {{{
> Author(models.Model):
> name = models.CharField(max_length=250)
>
> Book(models.Model):
> author_name = models.CharField(max_length=250)
> book_category = models.CharField(max_length=250)
> }}}
>
> Here is simplest query I can get to reproduce:
>
> {{{
> (Author.objects
> .annotate(min_valuable_count=Subquery(
> Book.objects
> .filter(author_name=OuterRef('name'))
> .annotate(cnt=Count('book_category'))
> .filter(cnt__gt=3)
> .order_by('cnt')
> .values('cnt')[:1],
> output_field=models.IntegerField()
> )))
> }}}
>
> And I get an error:
>
> {{{
> psycopg2.ProgrammingError: missing FROM-clause entry for table "U0"
> LINE 1: ... "core_author" GROUP BY "core_author"."id", "U0"."id" ...
> ^
> }}}
>
> Here is SQL:
>
> {{{
> SELECT "core_author"."id", "core_author"."name", (
> SELECT COUNT(U0."book_category") AS "cnt"
> FROM "core_book" U0 WHERE U0."id" = ("core_author"."chat_id")
> GROUP BY U0."id" HAVING COUNT(U0."book_category") > 3
> ORDER BY "cnt" ASC LIMIT 1)
> AS "min_valuable_count"
> FROM "core_author"
> GROUP BY "core_author"."id", "U0"."id"
> }}}
>
> If I remove line {{{.filter(cnt__gt=3)}}}, last {{{GROUP BY}}} disappears
> and query stops raising error:
>
> {{{
> SELECT "core_author"."id", "core_author"."name", (
> SELECT COUNT(U0."book_category") AS "cnt"
> FROM "core_book" U0 WHERE U0."id" = ("core_author"."chat_id")
> GROUP BY U0."id" HAVING COUNT(U0."book_category") > 3
> ORDER BY "cnt" ASC LIMIT 1)
> AS "min_valuable_count"
> FROM "core_author"
> }}}
>
> Is there any way to remove {{{GROUP BY}}} in outer query without removing
> {{{.filter(cnt__gt=3)}}} in subquery?
New description:
I want to get authors and annotate minimal count of books in category if
it is greater than three.
Book and Author models and are not connected with ForeignKey fields (this
is abstract and simplified, there is a reason):
{{{
Author(models.Model):
name = models.CharField(max_length=250)
Book(models.Model):
author_name = models.CharField(max_length=250)
book_category = models.CharField(max_length=250)
}}}
Here is simplest query I can get to reproduce:
{{{
(Author.objects
.annotate(min_valuable_count=Subquery(
Book.objects
.filter(author_name=OuterRef('name'))
.annotate(cnt=Count('book_category'))
.filter(cnt__gt=3)
.order_by('cnt')
.values('cnt')[:1],
output_field=models.IntegerField()
)))
}}}
And I get an error:
{{{
psycopg2.ProgrammingError: missing FROM-clause entry for table "U0"
LINE 1: ... "core_author" GROUP BY "core_author"."id", "U0"."id" ...
^
}}}
Here is SQL:
{{{
SELECT "core_author"."id", "core_author"."name", (
SELECT COUNT(U0."book_category") AS "cnt"
FROM "core_book" U0 WHERE U0."id" = ("core_author"."chat_id")
GROUP BY U0."id" HAVING COUNT(U0."book_category") > 3
ORDER BY "cnt" ASC LIMIT 1)
AS "min_valuable_count"
FROM "core_author"
GROUP BY "core_author"."id", "U0"."id"
}}}
If I remove line {{{.filter(cnt__gt=3)}}}, last {{{GROUP BY}}} disappears
and query stops raising error:
{{{
SELECT "core_author"."id", "core_author"."name", (
SELECT COUNT(U0."book_category") AS "cnt"
FROM "core_book" U0 WHERE U0."id" = ("core_author"."chat_id")
GROUP BY U0."id"
ORDER BY "cnt" ASC LIMIT 1)
AS "min_valuable_count"
FROM "core_author"
}}}
Is there any way to remove {{{GROUP BY}}} in outer query without removing
{{{.filter(cnt__gt=3)}}} in subquery?
Is {{{qs.query.group_by = None}}} ok?
--
--
Ticket URL: <https://code.djangoproject.com/ticket/30099#comment:5>
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