unique_together fails when referencing columns from base and child class

[Claus Conrad]

Not sure whether this bug belongs to "System checks", "ORM" or "Migrations", but thought I'd report it:

class Foo(models.Model):

url = models.URLField("URL", blank=True)

class Bar(Foo):

blip = models.CharField(max_length=10)
class Meta:

unique_together = (

'url',
'blip'

)

---

$ python manage.py check
System check identified no issues (0 silenced).

---

$ python manage.py makemigrations
$ python manage.py migrate

File "/usr/lib/python3.3/site-packages/Django-1.7b1-py3.3.egg/django/db/backends/utils.py", line 61, in execute

return self.cursor.execute(sql, params)

psycopg2.ProgrammingError: column "url" named in key does not exist

[Shai Berger]

This cannot work when you are using multi-table inheritance -- the two columns are in separate tables, and you cannot place a cross-table constraint.

This probably belongs in "system checks".

It can work if the parent is abstract.

(accepting based on report, with no attempt to reproduce)
(I am hesitant to mark it, not being familiar enough with the checks code, but this is probably an easy-pickings ticket)

[adrien]

I'm able to reproduce.

[adrien]

Digging in the code, I would say this belongs to Migrations.

[Shai Berger]

@adrien: for this to belong in migrations, you need to point out something that migrations could do to fix it.

Please leave this in "system checks" until you can produce an SQL snippet that works on some database backend, and creates the expected constraint.

[Marc Egli]

Pull request: ​https://github.com/django/django/pull/2548

[Simon Charette <charette.s@…>]

In 0bcc92c6917738caa2f08ec16d26fad62974fb47:

Fixed #22356 -- Added a check to make sure unique_together fields are local.