On 6 syys, 11:22, Alex Hill <[email protected]> wrote:
> Hi Anssi,
>
> Thanks for your feedback! Responses inline.
>
>   1. It should not be assumed that the primary key is the field needed
>
> > in the inner query. We do have foreign keys to other fields, and one
> > can use this approach without foreign keys at all.
>
> Hmm, yes. Thinking about it, this seems like the biggest obstacle to
> implementing the query-wrapping approach.
>
> The reason I proposed just selecting the PK was to mirror the behaviour of
> QuerySet when passed to __in, as happens here:
>
> https://github.com/django/django/blob/master/django/db/models/query.p...
>
> But since we're talking about raw SQL, we'd want maximum flexibility - so
> would we need to introduce a ValuesRawQuerySet in order to select arbitrary
> columns? It seems that would be the approach that most closely mirrors
> QuerySet.

The ValuesRawQuerySet might be a good idea. Granted, the use cases for
it are hard to come by apart of support for subqueries... One might
say we have implemented a really fancy way to do cursor.execute();
cursor.fetchall()... :)

Another way is to have a pre_subselect hook, and wrap the raw SQL with
the right column selected automatically using that.

 - Anssi

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