python - Finding events that happened on the same day in Django -

i have person model , people can have jobs:

class person(models.model):     name = textfield()     birth_date = datefield()  class job(models.model):     name = textfield()     start_date = datefield()     person = foreignkey('person') 

i want find people started work on birthday.

now, if wanted find people started work on exact birthday, i'd use:

from django.db.models import f person.objects.filter(birth_date=f('job__start_date')) 

but returns no one, because no 1 assigned job born (hopefully).

i can find started work on april 1st:

person.objects.filter(birth_date__month=4, birth_date__day=1) 

but, if try combine find people started work during birthday month:

from django.db.models import f person.objects.filter(birth_date__month=f('job__start_date__month')) 

i get:

fielderror @ /data/explorer/ cannot resolve keyword u'month' field. join on 'start_date' not permitted 

how can find people started work on birthday?

lookups on date(time) fields in f expressions not supported in django. there still way, hacky may be.

from django.db import connection django.db.models import f  start_month = connection.ops.date_extract_sql('month', '%s.start_date' % job._meta.db_table) start_day = connection.ops.date_extract_sql('day', '%s.start_date' % job._meta.db_table) birth_month = connection.ops.date_extract_sql('month', 'birth_date') birth_day = connection.ops.date_extract_sql('day', 'birth_date')  # trigger join , make job table available # otherwise next query fail (there's less hacky way this) persons = person.objects.filter(job=f('job__pk'))  persons.extra(     {         'start_month': start_month,         'start_day': start_day,         'birth_month': birth_month,         'birth_day': birth_day     },     where=['start_day=birth_day , start_month=birth_month'] )