3. How to enable sorting on calculated fields?¶
Django adds sorting capabilities on fields which are attributes on the models.
When you add a calculated field Django doesn’t know how to do a
order_by, so it doesn’t add sorting capability on that field.
If you want to add sorting on a calculated field, you have to tell Django what to pass to
order_by. You can do this by setting the
admin_order_field attribute on the calculated field method.
You start from the admin you wrote in the previous chapter (How to optimize queries in Django admin?).:
hero_count.admin_order_field = '_hero_count' villain_count.admin_order_field = '_villain_count'
With these changes your admin becomes:
@admin.register(Origin) class OriginAdmin(admin.ModelAdmin): list_display = ("name", "hero_count", "villain_count") def get_queryset(self, request): queryset = super().get_queryset(request) queryset = queryset.annotate( _hero_count=Count("hero", distinct=True), _villain_count=Count("villain", distinct=True), ) return queryset def hero_count(self, obj): return obj._hero_count def villain_count(self, obj): return obj._villain_count hero_count.admin_order_field = '_hero_count' villain_count.admin_order_field = '_villain_count'
Here is the admin sorted on