Opened 12 years ago
Closed 10 years ago
#19018 closed Bug (fixed)
m2m relationships with a through field don't respect types.
Reported by: | Justin Lilly | Owned by: | nobody |
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Component: | Database layer (models, ORM) | Version: | 1.4 |
Severity: | Normal | Keywords: | |
Cc: | Triage Stage: | Accepted | |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
I ran into an issue today in which an empty list was returned from a Queryset when it should have been a blatant failure.
Given the models in https://github.com/django/django/blob/master/tests/modeltests/m2m_through/models.py
The following returns an empty queryset:
Group.objects.filter(members__in=[Friendship(pk=9)])
Change History (7)
comment:1 by , 12 years ago
Type: | Uncategorized → Bug |
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comment:2 by , 12 years ago
Triage Stage: | Unreviewed → Accepted |
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comment:3 by , 12 years ago
comment:4 by , 12 years ago
(Also not specific to __in
queries, same is true of a simple __exact
match on an FK field).
comment:6 by , 12 years ago
So looking at this mostly for my own edification.
A higher level place this could be checked would be db.models.where.Constraint.process
otherwise: db.models.fields.related.RelatedField.get_db_prep_lookup
and db.models.fields.related.RelatedField._pk_trace
seem like the best places to tackle this.
However unless a patch is pretty quick, it seems worth improving the docs, at least in the interim, to clarify that lookup values for model instances will always be converted to a simple pk value for database lookups.
comment:7 by , 10 years ago
Resolution: | → fixed |
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Status: | new → closed |
Fixed as part of 34ba86706f0db33d9a0ab44e4abb78703e7262a9:
Fixed #14334 -- Query relation lookups now check object types.
I don't believe this bug is specific to m2ms or through models at all. In general, currently you can pass any iterable of instances of any model to any
__in
query and the ORM will happily use the PKs of the models you give it, without checking whether they are an instance of the right model class (or a subclass, or raw PK values which is also supported).