Django : Filter query based on custom function
You may not be able to, instead you can post-process the queryset with a list comprehension or generator expression.
For example:
[x for x in Q if x.somecond()]
The answer by Ignacio is interesting, but it does not return a queryset. This one does:
def users_by_role(role):
users = User.objects.all()
ids = [user.id for user in users if user.role == role]
return users.filter(id__in=ids)
I just had a similar issue. The problem was i had to return a QuerySet instance. A quick solution for me was to do something like this:
active_serv_ids = [service.id for service in Service.objects.all() if service.is_active()]
nserv = Service.objects.filter(id__in=active_serv_ids)
I'm pretty sure this is not the prettiest and performant way to do this, but it works for me.
A more verbose way of doing this would be:
active_serv_ids = []
for service in Service.objects.all():
if service.is_active():
active_serv_ids.append(service.id)
nserv = Service.objects.filter(id__in=active_serv_ids)
I would suggest you to use a custom manager for your class, like this you could use :
nserv = service.objects.are_active()
This would be achieved with something like:
class ServiceManager(models.Manager):
def are_active(self):
# use your method to filter results
return you_custom_queryset
See custom managers