values_list throws interesting error when ordering by an extra column

[Sven R. Kunze]

MyModel.objects.extra(select={'my_column': 'adas'}).order_by('my_column').values_list('id', flat=True)

ProgrammingError: column "adas" does not exist
LINE 1: ...arch3_beleg"."id" FROM "modarch3_beleg" ORDER BY (adas) ASC ...

There's already a similar ticket (but it's closed as fixed) https://code.djangoproject.com/ticket/14930

[Tim Graham]

As noted ​in the docs, we aren't fixed bugs that involved QuerySet.extra().

[Sven R. Kunze]

How are we supposed to construct such queries then?

As usual the given example is minimal: so the actual working flow goes like this:

# 1 create complex queryset
... more code
# 2 add extra select and where
... more code
# 3 add order (maybe referring to the extra column)
... more code
# 4 wrap paginator around queryset
... more code
# 5 create values_list of paged queryset
... more code
# 6 evaluate <<<< crash

[Tim Graham]

If you have trouble using the ​expressions API, please ask using our support channels: TicketClosingReasons/UseSupportChannels.

[Sven R. Kunze]

I was able to rewrite the extra statement using a combination of Expression (for select) and extra (for where). So, I think we are set for now.

If you really consider deprecating extra, there would need to be a facility to add custom where clauses.

[Sven R. Kunze]

@timgraham thanks for pointing me at the docs. :)