Thanks Malcolm for a speedy response!
I guess my best bit is to somehow output the QuerySet into a list
which I can then order myself (although this seems a bit ugly!), or
have a rethink about the design of the two models.
Thanks again,
Mike.
On Jul 9, 2:07 pm, Malcolm Tredinnick <[EMAIL PROTECTED]>
wrote:
> On Wed, 2008-07-09 at 05:51 -0700, [EMAIL PROTECTED] wrote:
>
> [...]
>
> > I tried using the order_by with two sets of dates:
>
> > .order_by('-related_name_to_model__date_field_in_B', '-
> > date_field_in_A')
>
> > However, this just produces a queryset that is partitioned into two
> > separate date orderings.
>
> > What I'm asking is if there is anyway to "intermix" the dates so that
> > ALL of the Model As appear in date order, even if they do not have a
> > related Model B date?
>
> No, because ordering is done at the SQL level and Django converts that
> ordering tuple to a sequence of ordering columns. What is happening here
> (why the sets appear to be partitioned) is because all rows that don't
> have a date field in B have a NULL in that column after the outer join.
> All those NULLs sort together (whether they sort first or last is
> database dependent) and then model A date field is used as a secondary
> ordering to distinguish any rows that have sorted together for the "date
> in B" columns (e.g. the NULLs).
>
> If you were writing the raw SQL, you could do this with a coalesce
> statement in the ordering clause. Right now that kind of stuff isn't
> possible to insert directly via Django, although you could do it by
> subclassing Query (and then QuerySet) if you were really keen. Adding a
> way to have "smart" ordering objects (you pass in an object and Django
> will call the as_sql() method on it, for example) will probably happen
> at some point, but it's not high priority at the moment.
>
> Regards,
> Malcolm
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