values_list(flat=True) returns ValuesListQuerySet, not list

[Mark Tranchant]

The documentation should be updated to clarify that the structure returned by a values_list queryset with flat=True is not a plain list, but a ValuesListQuerySet. Alternatively, the code should actually output a list.

I spent a while struggling to understand why I couldn't use the Python x.count(y) function on the output of such a query before realizing that I wasn't working with a Python list:

> rlist = Rpt.objects.values_list('status', flat=True)
> type(rlist)
  django.db.models.query.ValuesListQuerySet
> rlist.count(1)
  TypeError: count() takes exactly 1 argument (2 given)
> rlist2 = list(Rpt.objects.values_list('status', flat=True))
> rlist2.count(1)
  6

[Baptiste Mispelon]

Sounds like a reasonable addition.

[Daniele Procida]

I have tentatively reserved this ticket for first-time committers who take part in the ​Don't be afraid to commit workshop at the ​DjangoCon Europe 2013 sprints on 18th and 19th May.

If you want to tackle this ticket before then, please don't let the fact that it's assigned to me stop you. Feel free to re-assign it to yourself and do whatever you like to it.

[alextreme]

Added a patch to clarify the values_list() documentation.

[Baptiste Mispelon]

How about something like that:

Note that this method returns a VLQS which is an object that behaves like
a list. Most of the time this is enough, but if you require an actual python
list object, you can simply call list() on it (which will evaluate the queryset).

[alextreme]

Thanks, the ticket has been updated.

[Baptiste Mispelon]

Looks good. Thanks for the patch!

[Aymeric Augustin <aymeric.augustin@…>]

In 7b85ef9dfb83bd2f2cde46b9836b9fd12a033b26:

Fixed #20408 -- Clarified that values_list() doesn't return a list.

Thanks marktranchant, bmispelon, and alextreme.