Opened 10 years ago

Closed 10 years ago

#4849 closed (duplicate)

Nested Filters

Reported by: ben.stookey@… Owned by: Adrian Holovaty
Component: Database layer (models, ORM) Version: master
Severity: Keywords: filter, foreignkey
Cc: Triage Stage: Accepted
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: UI/UX:

Description

After review in #django I decided to post this as a bug.

3 and 4 should have the same output, shouldn't they?

>>> Article.objects.filter(tags=t1)   #1
[<Article: A1>, <Article: A2>]
>>> Article.objects.filter(tags=t2)   #2
[<Article: A1>]
>>> Article.objects.filter(tags=t1).filter(tags=t2)   #3
[]
>>> Article.objects.filter(tags=t1, tags=t2)   #4
[<Article: A1>]

Although 4 works, the syntax doesn't allow for someone working with a list of tags.

Here are the models:

class Tag(models.Model):
	name = models.CharField(maxlength=32, unique=True)

class Article(models.Model):
	title = models.CharField(maxlength=255)
	tags = models.ManyToManyField(Tag)

Change History (7)

comment:1 Changed 10 years ago by Collin Grady <cgrady@…>

Component: Core frameworkDatabase wrapper

comment:2 Changed 10 years ago by ben.stookey@…

I guess 4 wasn't actually working either because I can't pass "tags" twice. It only looked at t2:

>>> Article.objects.filter(tags=t2, tags=t1)
[<Article: A1>, <Article: A2>]

comment:3 Changed 10 years ago by nick.lane.au@…

As you said, Article.objects.filter(tags=t2, tags=t1) won't work because you can't pass duplicate keyword arguments for "tags". For this you could use:

>>> Article.objects.filter(tags__in=(t1, t2)).distinct()
[<Article: A1>, <Article: A2>]

comment:4 Changed 10 years ago by ben.stookey@…

The problem is, that is an OR relationship and I'm looking for AND. Only those articles that have both tags. Shouldn't number 3 do that?

comment:5 Changed 10 years ago by nick.lane.au@…

Sorry, I see what you mean now.

comment:6 Changed 10 years ago by Malcolm Tredinnick

Triage Stage: UnreviewedAccepted

This is a known bug. I thought it was a duplicate of something, but I can't find it now. I'm back to working on the QuerySet rewrite, so it's something that gets fixed as part of that. Conjunctions involving the same column do not work at the moment.

comment:7 Changed 10 years ago by Malcolm Tredinnick

Resolution: duplicate
Status: newclosed

Dupe of #4464.

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