How to filter the latest amended laws in django admin site?
below is the description of models:
- I have a Law model
- Each law many Versions
- Each version has many Translations
- Each translation has many annotations
I want to get the latest amended laws in the django admin site. So, I created a proxy model of Law.
and in the the admin file of law I have this:
@admin.register(LatestAmendedLaws) class LatestAmendedLawsAdmin(admin.ModelAdmin): list_display = ("id", "rs_number", "created") def get_queryset(self, request): latest_translation_datetime = Translation.objects.latest("created").created return ( super() .get_queryset(request) .filter(created__gte=latest_translation_datetime) )
this script doesn't return the correct latest amended laws. because it filters based on the created field of law. but it should be based on the latest created/updated date of translations that are associated with the law.
Maybe you can try like this:
django.db.models import SubQuery, OuterRef query = Translation.objects.filter(law_version__law_id=OuterRef('pk')).order_by('created') LatestAmendedLaws.objects.annotate(max_date=Sunquery(query.values('created')[:1])).filter(versions__translations__created=F('max_date'))
Here I am annotating the maximum created time of Translation and annotate it with LatestAmendedLaws queryset using Subquery. Then I ran a filter based on the annotated fields.