id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
34786	Multiple Q objects in the same .filter() behave oddly with ManyToMany relationships	Jon Janzen	nobody	"I found something odd, this may be intentional behavior (if undocumented, AFAICT) or might be covered by another bug report. If so, I apologize for the dupe.

Basically, I would have expected the following to behave the same, but they do not:

{{{#!python
Test.objects.filter(Q(tags=1)).filter(Q(tags=2))
Test.objects.filter(Q(tags=1), Q(tags=2))
}}}

(Where Test is some model with a Many2Many relationship called ""tags"" and the model on the  other end of ""tags"" has 2 objects with IDs 1 and 2)

In my testing, the first query returns an ""and"" of the results, that is, only Test objects that are tagged with BOTH Tag 1 and Tag 2, while the second query returns no results. Furthermore, `Test.objects.filter(Q(tags=1) & Q(tags=2))` also returns no results.

I have a system that converts GitHub-like query expressions (e.g. ""is:pr is:open author:bigfootjon"") into Django ORM and it previously made a call like `ModelToSearch.objects.filter(*q_expressions)` until I hit this ""bug"" when I was adding support for searching via a ManyToMany field. Now I just loop over `q_expressions` and call `.filter()` repeatedly so I'm not blocked by this, but I thought it was odd. I checked the docs (https://docs.djangoproject.com/en/4.2/topics/db/queries/) and didn't see anything about this edge-case mentioned.

I've prepared a test-project that reproduces this behavior with instructions on how to show the weirdness: https://github.com/bigfootjon/djangoqbugreport

(In that repo I specify testing against Django 4.2.4, but this also reproduces on Django 5.0 at commit `517d3bb4dd17e9c51690c98d747b86a0ed8b2fbf` aka `Django==5.0.dev20230819082943`)

I'm not sure whether to classify this as a bug or not, but if it is not a bug I think it should be documented (somehow, I don't quite understand the problem well enough myself to document it).

I'm afraid I don't quite have the ORM terminology to express this bug clearly so I apologize if this isn't clear in any way, I'm happy to answer questions."	Uncategorized	closed	Database layer (models, ORM)	4.2	Normal	invalid			Unreviewed	0	0	0	0	0	0