Cron string parser and scheduler for Python
Cron-converter provides a Cron string parser ( from string/lists to string/lists ) and iteration for the datetime object with a cron like format.
This project would be a transposition in Python of JS cron-converter by roccivic.
pip install cron-converter
from cron_converter import Cron
cron_instance = Cron()
or
cron_instance = Cron('*/10 9-17 1 * *')
or (with constructor options)
cron_instance = Cron('*/10 9-17 1 * *', {
'output_weekday_names': True,
'output_month_names': True
})
# Every 10 mins between 9am and 5pm on the 1st of every month
# In the case of the second or third creation method this step is not required
cron_instance.from_string('*/10 9-17 1 * *')
# Prints: '*/10 9-17 1 * *'
print(cron_instance.to_string())
# Alternatively, you could print directly the object obtaining the same result:
# print(cron_instance) # Prints: '*/10 9-17 1 * *'
# Prints:
# [
# [ 0, 10, 20, 30, 40, 50 ],
# [ 9, 10, 11, 12, 13, 14, 15, 16, 17 ],
# [ 1 ],
# [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ],
# [ 0, 1, 2, 3, 4, 5, 6 ]
# ]
print(cron_instance.to_list())
cron_instance.from_list([[0], [1], [1], [5], [0,2,4,6]])
# Prints: '0 1 1 5 */2'
print(cron_instance.to_string())
Possible options:
cron_instance = Cron(None, {
'output_weekday_names': True,
'output_month_names': True
})
cron_instance.from_string('*/5 9-17/2 * 1-3 1-5')
# Prints: '*/5 9-17/2 * JAN-MAR MON-FRI'
print(cron_instance)
or
cron_instance = Cron('*/5 9-17/2 * 1-3 1-5', {
'output_weekday_names': True,
'output_month_names': True
})
# Prints: '*/5 9-17/2 * JAN-MAR MON-FRI'
print(cron_instance)
cron_instance = Cron('*/5 9-17/2 * 1-3 1-5', {
'output_hashes': True
})
# Prints: 'H/5 H(9-17)/2 H 1-3 1-5'
print(cron_instance.to_string())
# Parse a string to init a schedule
cron_instance.from_string('*/5 * * * *')
# Raw datetime without timezone info (not aware)
reference = datetime.now()
# Get the iterator, initialised to now
schedule = cron_instance.schedule(reference)
# Calls to .next() and .prev()
# return a Datetime object
# Examples with time now: '2021-01-01T09:32:00
# Prints: '2021-01-01T09:35:00'
print(schedule.next().isoformat())
# Prints: '2021-01-01T09:40:00'
print(schedule.next().isoformat())
# Reset
schedule.reset()
# Prints: '2021-01-01T09:30:00'
print(schedule.prev().isoformat())
# Prints: '2021-01-01T09:25:00'
print(schedule.prev().isoformat())
Be sure to init your cron-converter instance with a TZ aware datetime for this to work!
A Scheduler has two optional mutually exclusive arguments: start_date
or timezone_str
.
By default (no parameters), a Scheduler start count with a UTC datetime ( utcnow() ) if you not specify any start_date
datetime object.
If you provide timezone_str
the Scheduler will start count from a localized now datetime ( datetime.now(tz_object) ).
Example starting from localized now datetime
from cron_converter import Cron
cron = Cron('0 0 * * *')
schedule = cron.schedule(timezone_str='Europe/Rome')
# Prints: result datetime + utc offset
print(schedule.next())
Example using pytz:
from pytz import timezone
from datetime import datetime
from cron_converter import Cron
tz = timezone('Europe/Rome')
local_date = tz.localize(datetime(2021, 1, 1))
cron = Cron('0 0 * * *')
schedule = cron.schedule(start_date=local_date)
next_schedule = schedule.next()
next_next_schedule = schedule.next()
# Prints: '2021-01-01T00:00:00+01:00'
print(next_schedule.isoformat())
# Prints: '2021-01-02T00:00:00+01:00'
print(next_next_schedule.isoformat())
Example using python_dateutil:
import dateutil.tz
from datetime import datetime
from cron_converter import Cron
tz = dateutil.tz.gettz('Asia/Tokyo')
local_date = datetime(2021, 1, 1, tzinfo=tz)
cron = Cron('0 0 * * *')
schedule = cron.schedule(start_date=local_date)
next_schedule = schedule.next()
next_next_schedule = schedule.next()
# Prints: '2021-01-01T00:00:00+09:00'
print(next_schedule.isoformat())
# Prints: '2021-01-02T00:00:00+09:00'
print(next_next_schedule.isoformat())
It's possible to compare the Cron object schedules frequency. Thanks @zevaverbach.
# Hours
Cron('0 1 * * 1-5') == Cron('0 2 * * 1-5') # True
Cron('0 1,2,3 * * 1-5') > Cron('0 1,23 * * 1-5') # True
# Minutes
Cron('* 1 * * 1-5') == Cron('0-59 1 * * 1-5') # True
Cron('1-30 1 * * 1-5') > Cron('1-29 1 * * 1-5') # True
# Days
Cron('* 1 1 * 1-5') == Cron('0-59 1 2 * 1-5') # True
Cron('* 1 1,2 * 1-5') > Cron('* 1 6 * 1-5') # True
# Month
Cron('* 1 1 11 1-5') == Cron('* 1 1 1 1-5') # True
Cron('* 1 6 * 1-5') > Cron('* 1 6 1 1-5') # True
# WeekDay
Cron('* 1 1 11 *') == Cron('* 1 1 11 0-6') # True
Cron('* 1 6 * 1-5') > Cron('* 1 6 * 1-4') # True
Cron-converter is NOT able to do second repetition crontabs form.
git clone https://github.com/Sonic0/cron-converter
cd cron-converter
...
python -m unittest discover -s tests/unit
python -m unittest discover -s tests/integration
This repo is part of a projects group, called Cron-Converter. Its related repositories: