#36210: Support queries where lhs is CompositePrimaryKey and rhs is Subquery
-------------------------------------+-------------------------------------
Reporter: Jacob | Owner: Jacob Walls
Walls |
Type: New | Status: assigned
feature |
Component: Database | Version: 5.2
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
This query is not currently supported (models drawn from composite_pk test
suite):
{{{
subquery = Subquery(User.objects.filter(pk=OuterRef("pk")).values("pk"))
queryset = Comment.objects.filter(pk=subquery)
}}}
----
{{{#!py
File "/django/source/django/db/models/fields/tuple_lookups.py", line 56,
in get_prep_lookup
self.check_rhs_is_supported_expression()
File "/django/source/django/db/models/fields/tuple_lookups.py", line 79,
in check_rhs_is_supported_expression
raise ValueError(
ValueError: 'exact' subquery lookup of 'pk' only supports OuterRef and
QuerySet objects (received 'Subquery')
}}}
----
The version without explicit `Subquery` (and adding `[:1]`) also fails:
{{{
File "/django/source/django/db/models/lookups.py", line 384, in
get_prep_lookup
raise ValueError(
ValueError: The QuerySet value for the exact lookup must have 2 selected
fields (received 1)
}}}
On Oracle the failure looks like this, but this is probably a separate
issue:
{{{#!py
django.db.utils.DatabaseError: ORA-01796: this operator cannot be used
with lists
Help: https://docs.oracle.com/error-help/db/ora-01796/
}}}
----
[https://github.com/django/django/pull/19206 PR] to kick off discussion
addresses all but the Oracle failure, which might worth looking at
separately, perhaps a deeper issue?
--
Ticket URL: <https://code.djangoproject.com/ticket/36210>
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