def queryset(self, request, queryset):
if not self.value() or self.value() == 0:
return queryset
return Volunteer.objects.filter(
tasks__edition=Edition.get_previous()).exclude(
tasks__edition=Edition.get_current()).distinct()
def lookups(self, request, model_admin):
edition = Edition.get_previous()
return [(edition.id, edition.name)]