django - Getting upcoming birthdays using 'date of birth' DateField -

i'm trying birthdays in upcoming 20 days, given below person model:

class person(models.model):     dob = models.datefield()  # date of birth 

there similar questions on (here , here), these not cover use case, i'm storing date of birth instead of next birthday or timefield.

i've tried things following:

from datetime import timedelta, date today = date.today() next_20_days = today+timedelta(days=20) person.objects.filter(dob__month=today.month, dob__day__range=[today.day, next_20_days.day]) 

... fielderror: unsupported lookup 'day' datefield or join on field not permitted.

when e.g. person.objects.filter(dob__month=today.month, dob__day=next_20_days.day), results 20 days now. potentially go on each of 20 days in loop, seems rather ineffective.

any idea on how proper way?

fyi, ended doing following works me , not require raw sql. improvements welcomed :-)

# upcoming birthdays in list (which ordered) amount of days specified def get_upcoming_birthdays(person_list, days):     person_list= person_list.distinct()  # ensure persons in list once     today = date.today()     doblist = []     doblist.extend(list(person_list.filter(dob__month=today.month, dob__day=today.day)))     next_day = today + timedelta(days=1)     day in range(0, days):         doblist.extend(list(person_list.filter(dob__month=next_day.month, dob__day=next_day.day, dod__isnull=true)))         next_day = next_day + timedelta(days=1)     return doblist