#29021 closed Bug (needsinfo)

Weird behavior of foreign key lookup and annotate F expression

Reported by: Paul Owned by: nobody
Component: Database layer (models, ORM) Version: 1.10
Severity: Normal Keywords: django-model, foreign-key
Cc: Triage Stage: Unreviewed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description (last modified by Paul)

class Sentence(Model):
    name = CharField()
    
class Tokens(Model):
    token = CharField()
    sentence = ForeignKey(Sentence, related_name='tokens')
Sentence.objects.annotate(n=Count('tokens', distinct=True)).filter(n=5).filter(tokens__name__in=['se']).annotate(n0=F('tokens')).filter(tokens__name__in=['faire']).annotate(n1=F('tokens')).filter(tokens__name__in=['faire']).annotate(n2=F('tokens')).filter(tokens__name__in=['un']).annotate(n3=F('tokens')).filter(tokens__name__in=['avoir']).annotate(n4=F('tokens'))

Above code generates the following query:

    SELECT "sentence"."id", "sentence"."name" COUNT(DISTINCT "token"."id") AS "n", T3."id" AS "n0", T4."id" AS "n1", T4."id" AS "n2", T6."id" AS "n3", T6."id" AS "n4" FROM "sentence" LEFT OUTER JOIN "token" ON ("sentence"."id" = "token"."sentence_id") INNER JOIN "token" T3 ON ("sentence"."id" = T3."sentence_id") INNER JOIN "token" T4 ON ("sentence"."id" = T4."sentence_id") INNER JOIN "token" T5 ON ("sentence"."id" = T5."sentence_id") INNER JOIN "token" T6 ON ("sentence"."id" = T6."sentence_id") INNER JOIN "token" T7 ON ("sentence"."id" = T7."sentence_id") WHERE (T3."name" IN (se) AND T4."name" IN (faire) AND T5."name" IN (un) AND T6."name" IN (avoir) AND T7."name" IN (faire)) GROUP BY "word_frword"."id", T3."id", T4."id", T6."id" HAVING COUNT(DISTINCT "token"."id") = 5

There is T4."id" AS "n2" instead of T5."id" AS "n2", so chaining is working incorrectly.

Change History (6)

comment:1 Changed 11 months ago by Tim Graham

Resolution: invalid
Status: newclosed

This looks like an "is it a bug?" or "how do I do X?" question which should be asked on our support channels rather than in the bug tracker. If you can provide a more minimal query and explain why Django's behavior is incorrect, feel free to reopen.

comment:2 Changed 11 months ago by Paul

Description: modified (diff)
Resolution: invalid
Status: closednew

comment:3 Changed 11 months ago by Paul

Description: modified (diff)

comment:4 Changed 11 months ago by Tim Graham

Is that the simplest queryset that demonstrates the issue?

comment:5 in reply to:  4 Changed 11 months ago by Paul

Replying to Tim Graham:

Is that the simplest queryset that demonstrates the issue?

The simplest will be with three words:

Sentence.objects.annotate(n=Count('tokens', distinct=True)).filter(n=5).filter(tokens__name__in=['se']).annotate(n0=F('tokens')).filter(tokens__name__in=['faire']).annotate(n1=F('tokens')).filter(tokens__name__in=['un']).annotate(n2=F('tokens'))

Query:

    SELECT "sentence"."id", "sentence"."name", COUNT(DISTINCT "token"."id") AS "n", T3."id" AS "n0", T4."id" AS "n1", T4."id" AS "n2" FROM "sentence" LEFT OUTER JOIN "token" ON ("sentence"."id" = "token"."sentence_id") INNER JOIN "token" T3 ON ("sentence"."id" = T3."sentence_id") INNER JOIN "token" T4 ON ("sentence"."id" = T4."sentence_id") INNER JOIN "token" T5 ON ("sentence"."id" = T5."sentence_id") WHERE (T3."name" IN (se) AND T4."name" IN (faire) AND T5."name" IN (un)) GROUP BY "word_frword"."id", T3."id", T4."id" HAVING COUNT(DISTINCT "token"."id") = 5

comment:6 Changed 11 months ago by Ramiro Morales

Resolution: needsinfo
Status: newclosed

Are you actually seeing this in Django 1.10 as per the ticket field? If so please try to test it on a newer version, e.g. 1.11 or even better 2.0. For two reasons: Django 1.10 support period has finished (https://www.djangoproject.com/weblog/2015/jun/25/roadmap/) and it could be this is a problem which is already solved.

What database backend are you using? Please reopen when you can provide this information.

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