#21554: incorrect SQL generated when using multiple inheritance
----------------------------------------------+----------------------------
Reporter: pegler | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: master
Severity: Normal | Keywords: multiple-
Triage Stage: Unreviewed | inheritance
Easy pickings: 0 | Has patch: 0
| UI/UX: 0
----------------------------------------------+----------------------------
Our application makes use of multiple-inheritance and we've just come
across an interesting bug. There is a test case attached and it fails
against the latest 1.4, 1.5, 1.6, and master versions. Though the reason
changes between versions 1.5 and 1.6.
The models:
{{{
class Person(models.Model):
name = models.CharField(max_length=50)
class Politician(models.Model):
politician_id = models.AutoField(primary_key=True)
title = models.CharField(max_length=50)
class Congressman(Person, Politician):
state = models.CharField(max_length=2)
class Senator(Congressman):
pass
}}}
The statement {{{ Senator.objects.get(politician_id=1) }}} produces
incorrect SQL for all versions, but is different between versions.
1.4.10 and 1.5.5 result in the error "DoesNotExist: Senator matching query
does not exist." due to it trying to join demo_politician onto
demo_senator via demo_senator.congressman_ptr_id instead of
demo_politician.politician_id
{{{
SELECT "demo_person"."id", "demo_person"."name", T5."politician_id",
T5."title", "demo_congressman"."politician_ptr_id",
"demo_congressman"."person_ptr_id", "demo_congressman"."state",
"demo_senator"."congressman_ptr_id"
FROM "demo_senator"
INNER JOIN "demo_congressman" ON ("demo_senator"."congressman_ptr_id" =
"demo_congressman"."person_ptr_id")
INNER JOIN "demo_person" ON ("demo_senator"."congressman_ptr_id" =
"demo_person"."id")
INNER JOIN "demo_politician" T5 ON ("demo_senator"."congressman_ptr_id" =
T5."politician_id")
WHERE "demo_congressman"."politician_ptr_id" = 1
}}}
1.6 and master results in the error "OperationalError: no such column:
demo_congressman.politician_id". It incorrectly thinks that politician_id
is on demo_congressman instead of demo_politician.
{{{
SELECT "demo_person"."id", "demo_person"."name",
"demo_congressman"."politician_id", "demo_congressman"."title",
"demo_congressman"."politician_ptr_id",
"demo_congressman"."person_ptr_id", "demo_congressman"."state",
"demo_senator"."congressman_ptr_id"
FROM "demo_senator"
INNER JOIN "demo_congressman" ON ( "demo_senator"."congressman_ptr_id" =
"demo_congressman"."person_ptr_id" )
INNER JOIN "demo_person" ON ( "demo_congressman"."person_ptr_id" =
"demo_person"."id" )
WHERE "demo_congressman"."politician_ptr_id" = 1
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/21554>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/049.f784db0c2cec3678d7f4f18f1025b919%40djangoproject.com.
For more options, visit https://groups.google.com/groups/opt_out.
