#31251: Unable to annotate a query that has an OuterRef already
-------------------------------------+-------------------------------------
Reporter: OJFord | Owner: nobody
Type: Bug | Status: new
Component: Database | Version: 3.0
layer (models, ORM) | Keywords: db,outerref,group
Severity: Normal | by,subquery,annotate
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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I'm trying to construct a query like:
{{{
cheapest_query = models.Subquery(qs.annotate(
groupbytype=models.OuterRef("type"),
).values("groupbytype")).annotate(
cheapest=models.Min("price"),
).values("cheapest"))
qs = qs.annotate(premium_over_cheapest=models.F("price") - cheapest_query)
}}}
However this fails in the second `annotate` (`cheapest=`) since
`ResolvedOuterRef` does not descend from `BaseExpression`; so it has no
`get_group_by_cols` method:
{{{
File "/usr/local/lib/python3.8/site-
packages/django/db/models/query.py", line 1078, in annotate
clone.query.set_group_by()
File "/usr/local/lib/python3.8/site-
packages/django/db/models/sql/query.py", line 1938, in set_group_by
inspect.getcallargs(annotation.get_group_by_cols, alias=alias)
AttributeError: 'ResolvedOuterRef' object has no attribute
'get_group_by_cols'
}}}
https://github.com/django/django/blob/master/django/db/models/expressions.py
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Ticket URL: <https://code.djangoproject.com/ticket/31251>
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