How to get a django QuerySet of all ForeignKeys of all objects in a Queryset

Question

I have a model (or actually 2 models, but the other is not that relevant)

class Foo(models.Model):
    ...
    bar = models.ForeignKey(Bar,
        ...
    )


        

Answer 1

you could use foo_queryset.bar_set.all() to get all instances of your Bar

foo_queryset = Foo.objects.filter(attr=value)
referenced_bars = foo_queryset.bar_set.all()

The Django documentation has more details.

Answer 2

foo_queryset = Foo.objects.filter(attr=value)
referenced_bars = Bar.objects.filter(id__in=foo_queryset.values('bar_id'))

Answer 3

bars = Bar.objects.filter(foo_set__attr=value)