update_or_create condicional com django

try:
    obj = Room.objects.get(
        id=id, # test with other fields if you want
    )
    if obj.modified_at < DATETIME:
        obj.capacity = 10
        obj.save()
    else:
        obj = Room.objects.create(
            # fields attributes
        )
except Room.DoesNotExist:
    obj = Room.objects.create(
        # fields attributes
    )

from django.db.models import F, Case, When
import datetime

your_date = datetime.datetime.now()
condition = Case(When(modified_at__lt=your_date,then=10),default=F('capacity'))

• Verificamos se modified_at é menor que your_date
• então o valor dessa condição é 10,
• senão, mantemos o mesmo valor do campo com F('capacity')

Room.objects.update_or_create(name='new_name',
           defaults={'name':'new_name','capacity':conditition})