TypeError: Unsupported deadline datetime.datetime(....)

Question

I'm trying to run a function periodically using IOLoop in Tornado. However, the following code gets the error?

TypeError: Unsupported deadline datetime.datetime(2021, 11, 11, 0, 35, 49, 445200)

from tornado.ioloop import IOLoop
import datetime

def schedule_next_email():
    # t = datetime.date.today() + datetime.timedelta(seconds=10)
    t = datetime.datetime.now() + datetime.timedelta(seconds=10)
    # t2 = datetime.datetime.combine(t, datetime.time.min)
    def wrapper():
        print('test')
        schedule_next_email()
    IOLoop.current().add_timeout(t, wrapper)  # Error

schedule_next_email() 

Ref: How to start Tornado periodic callback at a specific time?

Traceback (most recent call last):
  File "", line 1, in 
  File "", line 8, in schedule_next_email
  File "C:\Users\...\anaconda3\lib\site-packages\tornado\ioloop.py", line 585, in add_timeout
    raise TypeError("Unsupported deadline %r" % deadline)
TypeError: Unsupported deadline datetime.datetime(2021, 11, 11, 0, 47, 28, 944375)

Answer 1

add_timeout takes a timedelta, not a datetime, as the deadline argument, so just pass the timedelta directly:

from tornado.ioloop import IOLoop
import datetime

def schedule_next_email():
    t = datetime.timedelta(seconds=10)
    def wrapper():
        print('test')
        schedule_next_email()
    IOLoop.current().add_timeout(t, wrapper)

schedule_next_email() 

Make sure the IO loop starts in one way or another; I added IOLoop.current().start() to the end for testing purposes, though it may be different for production code.