Re: Combining queries? A "join" in Python?

On 08/27/2011 11:39 AM, graeme wrote:
> I have a some models related link this:
>
> A has a foreign key on B which has a foreign key on C
>
> I also have D with a foreign key on B, and E with a foreign key of C
>
> If I do A.filter(**args).select_related() I will get all the As, Bs,
> and Cs I want.
>
> How do I get the Ds with a foreign key on a B in my queryset
> (preferably filtered) and all Es with a foreign key on C (also
> preferably filtered)
>
> The best I have been able to come up with is to query for all the the
> Ds and Es I want, and combine them with the Bs and Cs in the view.
>
> I have a similar problem with another site, except that there not
> every B I want has an A with a foreignkey pointing to it, so I cannot
> just do select_related on A.
>
> I am not worried about doing an extra query or two per page. What I
> want to avoid is doing an extra query for each object in a lengthy
> list.
>
You can 'or' two query sets with the '|' operator

so do
queryset1 = Mymodel.objects.all().filter(...)
qyeryset2 = Mymodel.objects.all().filter(...)

combined = queryset1 | queryset2

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