#34945: annotate -> union -> values gives wrong values
-------------------------------------+-------------------------------------
Reporter: Tom | Owner: nobody
Carrick |
Type: Bug | Status: new
Component: Database | Version: 4.2
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 |
-------------------------------------+-------------------------------------
With the following code:
{{{
import uuid
from django.conf import settings
from django.contrib.auth import get_user_model
from django.db import models
from django.db.models.functions import Cast
class DocumentQuerySet(models.QuerySet):
def for_user(self, user):
return self.filter(things__user=user).union(
self.filter(other_things__user=user)
)
class Document(models.Model):
name = models.CharField()
id = models.UUIDField(default=uuid.uuid4, primary_key=True)
objects = DocumentQuerySet().as_manager()
class Thing(models.Model):
user = models.ForeignKey(
settings.AUTH_USER_MODEL, related_name="things",
on_delete=models.CASCADE
)
document = models.ForeignKey(
Document, related_name="things", on_delete=models.CASCADE
)
class OtherThing(models.Model):
user = models.ForeignKey(
settings.AUTH_USER_MODEL, related_name="other_things",
on_delete=models.CASCADE
)
document = models.ForeignKey(
Document, related_name="other_things", on_delete=models.CASCADE
)
def broken():
user = get_user_model().objects.first()
return Document.objects.annotate(
pk_str=Cast("pk", output_field=models.CharField())
).for_user(user).values_list("pk_str", flat=True)
}}}
Running `broken()`, I would expect to say the stringified UUIDs from the
Document model. Instead I get the `name`s. It also happens when using
`values()`. If not using either, it works just fine, and you can access
`document.pk_str` and it works just fine. After playing with this, it
seems to be because it's defined first in the model. If I move `id` to the
top, it actually returns the UUIDs, without the cast being applied. The
query (as far as I can tell from Django) looks fine:
{{{
(SELECT "testapp_document"."id" AS "col1", "testapp_document"."name" AS
"col2", ("testapp_document"."id")::varchar AS "pk_str" FROM
"testapp_document" INNER JOIN "testapp_thing" ON ("testapp_document"."id"
= "testapp_thing"."document_id") WHERE "testapp_thing"."user_id" = 1)
UNION (SELECT "testapp_document"."id" AS "col1", "testapp_document"."name"
AS "col2", ("testapp_document"."id")::varchar AS "pk_str" FROM
"testapp_document" INNER JOIN "testapp_otherthing" ON
("testapp_document"."id" = "testapp_otherthing"."document_id") WHERE
"testapp_otherthing"."user_id" = 1)
}}}
And logged from Postgres also looks correct:
{{{
(SELECT "testapp_document"."name" AS "col1", "testapp_document"."id" AS
"col2", ("testapp_document"."id")::varchar AS "pk_str" FROM
"testapp_document" INNER JOIN "testapp_thing" ON ("testapp_document"."id"
= "testapp_thing"."document_id") WHERE "testapp_thing"."user_id" = 1)
UNION (SELECT "testapp_document"."name" AS "col1", "testapp_document"."id"
AS "col2", ("testapp_document"."id")::varchar AS "pk_str" FROM
"testapp_document" INNER JOIN "testapp_otherthing" ON
("testapp_document"."id" = "testapp_otherthing"."document_id") WHERE
"testapp_otherthing"."user_id" = 1) LIMIT 21
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/34945>
Django <https://code.djangoproject.com/>
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