Dynamically update Django form field options using Ajax to GET new queryset
You can't do this from Django views side, ie, backend. You could try an ajax request for implementing this kind of requests, by sending a GET request to the server for populating the drop-down or whatever you are into.
For a simple example, you could referhere
How do I POST with jQuery/Ajax in Django?
EDIT
def update_subcategories(request): category = request.GET.get('category', None) sub_category = list(SubCategory.objects.filter(category__name__exact=category).values('name')) return JsonResponse(dict(sub_category=sub_category))Then in ajax response you could grab it like response.data.sub_category
Use ajax to send the category and retrieve subcategory elements.
For the category, send it via get request, and using the orm return the subcategories in a json format which you can show using jQuery.