#33450: Integer PK wrongly casted as UUID when using with a GenericForeignKey
model
with a UUID field
-------------------------------------+-------------------------------------
Reporter: Santos | Owner: nobody
Gallegos |
Type: Bug | Status: new
Component: Database | Version: 4.0
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 |
-------------------------------------+-------------------------------------
Hi, at Read the Docs we have migrated from Django 2.2 to 3.2, and we
encountered the following problem. In a model that makes use of a
GenericForeignKey field, and it has a UUID field as its pk will result in
Django casting the ID of the related model as UUID in some queries (the
related model makes use of the default BigAutoField). I was able to
reproduce this with the following models and using postgres as the DB
backend.
{{{#!python
from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import (
GenericForeignKey,
GenericRelation,
)
import uuid
class TTag(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4,
editable=False)
content_type = models.ForeignKey(ContentType,
on_delete=models.CASCADE)
object_id = models.PositiveIntegerField()
content = GenericForeignKey()
class TIntegration(models.Model):
tags = GenericRelation(TTag, related_query_name='integration')
}}}
The problematic queries:
{{{#!python
integration = TIntegration.objects.create()
tag = integration.tags.create()
r = TTag.objects.filter(integration=integration)
print(r.query)
# The next error is raised if the query is evaluated
# psycopg2.errors.UndefinedFunction: operator does not exist: bigint =
uuid
}}}
The query will result in the following SQL
{{{#!sql
SELECT "core_ttag"."id", "core_ttag"."content_type_id",
"core_ttag"."object_id" FROM "core_ttag" INNER JOIN "core_tintegration" ON
("core_ttag"."object_id" = "core_tintegration"."id" AND
("core_ttag"."content_type_id" = 7)) WHERE "core_tintegration"."id" =
00000000-0000-0000-0000-000000000001
}}}
Note as `core_tintegration"."id"` is being casted as an UUID when it
should be an integer (1). I was able to bisect the error to this commit
https://github.com/django/django/commit/1afbc96a75bd1765a56054f57ea2d4b238af3f4d.
Before that commit, the generated SQL is as follows:
{{{#!sql
SELECT "core_ttag"."id", "core_ttag"."content_type_id",
"core_ttag"."object_id" FROM "core_ttag" INNER JOIN "core_tintegration" ON
("core_ttag"."object_id" = "core_tintegration"."id" AND
("core_ttag"."content_type_id" = 7)) WHERE "core_tintegration"."id" = 1
}}}
We were able to work around this issue by changing the queries to
explicitly use the ID.
{{{#!python
TTag.objects.filter(integration__id=integration.id)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/33450>
Django <https://code.djangoproject.com/>
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