cron-converter 0.0.2

Cron string parser for Python

cron-converter

Cron-converter provides a Cron string parser ( from string/list to string/lists ) and iteration for the datetime object with a cron like format.
This project is a transposition in Python of JS [cron-converter](https://github.com/roccivic/cron-converter) by [roccivic](https://github.com/roccivic).

This project is WIP.

Install

Pip

pip install cron-converter

Use

from cron_converter import cron

Create a new instance

cron_instance = cron.Cron()

or

cron_instance = cron.Cron('*/10 9-17 1 * *')

or (with constructor options)

cron_instance = cron.Cron('*/10 9-17 1 * *', {
  'outputWeekdayNames': True,
  'outputMonthNames': True
})

Parse a cron string

# Every 10 mins between 9am and 5pm on the 1st of every month
# In 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())

# 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())

Parse an Array

cron_instance.from_list([[0], [1], [1], [5], [0,2,4,6]])

# Prints: '0 1 1 5 */2'
print(cron_instance.to_string())

Constructor options

outputWeekdayNames and outputMonthNames --> Default: false

cron_instance = Cron(None, {
  'outputWeekdayNames': True,
  'outputMonthNames': True
})
cron_instance.from_string('*/5 9-17/2 * 1-3 1-5')
# Prints: '*/5 *(10-16)/2 * JAN-MAR MON-FRI'
print(cron_instance)

or

cron_instance = Cron('*/5 9-17/2 * 1-3 1-5', {
  'outputWeekdayNames': True,
  'outputMonthNames': True
})
# Prints: '*/5 *(10-16)/2 * JAN-MAR MON-FRI'
print(cron_instance)

Get the schedule execution times. Example with raw Datetime

# Parse a string to init a schedule
cron_instance.from_string('*/5 * * * *')

# Optionally, use a reference Date or moment object
reference = datetime.now()  # Raw datetime without timezone info (not aware)
# Get the iterator, initialised to now
schedule = cron_instance.schedule(reference)

# Calls to .next() and .prev()
# return a Datetime object

# 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())

About DST

Be sure to init your cron-converter instance with a TZ aware datetime for this to work!

Example using pytz:

    from datetime import datetime
    import pytz
    from datetime import datetime
    from cron_converter import cron

    tz = pytz.timezone("Europe/Rome")
    local_date = tz.localize(datetime(2021, 1, 1))
    cron = cron.Cron('0 0 * * *')
    next_schedule = cron.schedule(local_date).next()
    # Prints: '2021-01-01T09:25:00+01:00'
    print(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.Cron('0 0 * * *')
    next_schedule = cron.schedule(local_date).next()
    # Prints: '2021-01-01T17:25:00+09:00'
    print(next_schedule.isoformat())

About seconds repeats

Cron-converter is NOT able to do second repetition crontabs form.

Test and build

git clone https://github.com/Sonic0/cron-converter
cd cron-converter
# TODO this step