Django formset_factory and foreign key efficiency

Question

I'm using Django's built in form.ModelForm and formset_factory to provide a set of forms for user input. Some of the fields on the form are select boxes and the data in those boxes are comprised of several fields so I expect several DB hits per each selection. However, when I add extra forms (e.g. by using the "extra" parameter) for each extra form it hits the DB again. For example, if there are 4 DB hits to make 1 selection, and there are 10 selections we expect 40 queries. But if I add 5 "extra" inlines, all of a sudden there are 4 * 10 * 5 for 200 queries. Doesn't formset_factory realize the selection box is the same for all of the inlines? Why so many database hits? Is there a better way to do this? In my opinion the selections should be generated once, and used for each selection box (i.e., 40 queries for this particular example).

Answer 1

I would definitely agree that the form sets should be smart enough to not query it so many times. I have run into this many times. I ended up doing something this:

class TestFormset(BaseModelFormSet):
    def __init__(self, *args, **kwargs):
        super(TestFormset,self).__init__(*args, **kwargs)

        awesome_models = AwesomeModel.objects.all()

        for form in self.forms:
            form.fields['awesome_model'].choices = [('', '--------')] + [(x.pk, x.name) for x in awesome_models]

This basically just runs one query, then manually setting the choices the particular field for each form in the form set.