croniter provides iteration for datetime object with cron like format
.. contents::
croniter provides iteration for the datetime object with a cron like format.
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Website: https://github.com/kiorky/croniter
.. image:: https://github.com/kiorky/croniter/actions/workflows/cicd.yml/badge.svg :target: https://github.com/kiorky/croniter/actions/workflows/cicd.yml
A simple example::
>>> from croniter import croniter
>>> from datetime import datetime
>>> base = datetime(2010, 1, 25, 4, 46)
>>> iter = croniter('*/5 * * * *', base) # every 5 minutes
>>> print(iter.get_next(datetime)) # 2010-01-25 04:50:00
>>> print(iter.get_next(datetime)) # 2010-01-25 04:55:00
>>> print(iter.get_next(datetime)) # 2010-01-25 05:00:00
>>>
>>> iter = croniter('2 4 * * mon,fri', base) # 04:02 on every Monday and Friday
>>> print(iter.get_next(datetime)) # 2010-01-26 04:02:00
>>> print(iter.get_next(datetime)) # 2010-01-30 04:02:00
>>> print(iter.get_next(datetime)) # 2010-02-02 04:02:00
>>>
>>> iter = croniter('2 4 1 * wed', base) # 04:02 on every Wednesday OR on 1st day of month
>>> print(iter.get_next(datetime)) # 2010-01-27 04:02:00
>>> print(iter.get_next(datetime)) # 2010-02-01 04:02:00
>>> print(iter.get_next(datetime)) # 2010-02-03 04:02:00
>>>
>>> iter = croniter('2 4 1 * wed', base, day_or=False) # 04:02 on every 1st day of the month if it is a Wednesday
>>> print(iter.get_next(datetime)) # 2010-09-01 04:02:00
>>> print(iter.get_next(datetime)) # 2010-12-01 04:02:00
>>> print(iter.get_next(datetime)) # 2011-06-01 04:02:00
>>>
>>> iter = croniter('0 0 * * sat#1,sun#2', base) # 1st Saturday, and 2nd Sunday of the month
>>> print(iter.get_next(datetime)) # 2010-02-06 00:00:00
>>>
>>> iter = croniter('0 0 * * 5#3,L5', base) # 3rd and last Friday of the month
>>> print(iter.get_next(datetime)) # 2010-01-29 00:00:00
>>> print(iter.get_next(datetime)) # 2010-02-19 00:00:00
All you need to know is how to use the constructor and the get_next
method, the signature of these methods are listed below::
>>> def __init__(self, cron_format, start_time=time.time(), day_or=True)
croniter iterates along with cron_format from start_time.
cron_format is min hour day month day_of_week, you can refer to
http://en.wikipedia.org/wiki/Cron for more details. The day_or
switch is used to control how croniter handles day and day_of_week
entries. Default option is the cron behaviour, which connects those
values using OR. If the switch is set to False, the values are connected
using AND. This behaves like fcron and enables you to e.g. define a job that
executes each 2nd Friday of a month by setting the days of month and the
weekday.
::
>>> def get_next(self, ret_type=float)
get_next calculates the next value according to the cron expression and
returns an object of type ret_type. ret_type should be a float or a
datetime object.
Supported added for get_prev method. (>= 0.2.0)::
>>> base = datetime(2010, 8, 25)
>>> itr = croniter('0 0 1 * *', base)
>>> print(itr.get_prev(datetime)) # 2010-08-01 00:00:00
>>> print(itr.get_prev(datetime)) # 2010-07-01 00:00:00
>>> print(itr.get_prev(datetime)) # 2010-06-01 00:00:00
You can validate your crons using is_valid class method. (>= 0.3.18)::
>>> croniter.is_valid('0 0 1 * *') # True
>>> croniter.is_valid('0 wrong_value 1 * *') # False
Be sure to init your croniter instance with a TZ aware datetime for this to work!
Example using pytz::
>>> import pytz
>>> tz = pytz.timezone("Europe/Paris")
>>> local_date = tz.localize(datetime(2017, 3, 26))
>>> val = croniter('0 0 * * *', local_date).get_next(datetime)
Example using python_dateutil::
>>> import dateutil.tz
>>> tz = dateutil.tz.gettz('Asia/Tokyo')
>>> local_date = datetime(2017, 3, 26, tzinfo=tz)
>>> val = croniter('0 0 * * *', local_date).get_next(datetime)
Example using python built in module::
>>> from datetime import datetime, timezone
>>> local_date = datetime(2017, 3, 26, tzinfo=timezone.utc)
>>> val = croniter('0 0 * * *', local_date).get_next(datetime)
Croniter is able to do second repetition crontabs form::
>>> croniter('* * * * * 1', local_date).get_next(datetime)
>>> base = datetime(2012, 4, 6, 13, 26, 10)
>>> itr = croniter('* * * * * 15,25', base)
>>> itr.get_next(datetime) # 4/6 13:26:15
>>> itr.get_next(datetime) # 4/6 13:26:25
>>> itr.get_next(datetime) # 4/6 13:27:15
You can also note that this expression will repeat every second from the start datetime.::
>>> croniter('* * * * * *', local_date).get_next(datetime)
Test for a match with (>=0.3.32)::
>>> croniter.match("0 0 * * *", datetime(2019, 1, 14, 0, 0, 0, 0))
True
>>> croniter.match("0 0 * * *", datetime(2019, 1, 14, 0, 2, 0, 0))
False
>>>
>>> croniter.match("2 4 1 * wed", datetime(2019, 1, 1, 4, 2, 0, 0)) # 04:02 on every Wednesday OR on 1st day of month
True
>>> croniter.match("2 4 1 * wed", datetime(2019, 1, 1, 4, 2, 0, 0), day_or=False) # 04:02 on every 1st day of the month if it is a Wednesday
False
For performance reasons, croniter limits the amount of CPU cycles spent attempting to find the next match.
Starting in v0.3.35, this behavior is configurable via the max_years_between_matches parameter, and the default window has been increased from 1 year to 50 years.
The defaults should be fine for many use cases.
Applications that evaluate multiple cron expressions or handle cron expressions from untrusted sources or end-users should use this parameter.
Iterating over sparse cron expressions can result in increased CPU consumption or a raised CroniterBadDateError exception which indicates that croniter has given up attempting to find the next (or previous) match.
Explicitly specifying max_years_between_matches provides a way to limit CPU utilization and simplifies the iterable interface by eliminating the need for CroniterBadDateError.
The difference in the iterable interface is based on the reasoning that whenever max_years_between_matches is explicitly agreed upon, there is no need for croniter to signal that it has given up; simply stopping the iteration is preferable.
This example matches 4 AM Friday, January 1st. Since January 1st isn't often a Friday, there may be a few years between each occurrence. Setting the limit to 15 years ensures all matches::
>>> it = croniter("0 4 1 1 fri", datetime(2000,1,1), day_or=False, max_years_between_matches=15).all_next(datetime)
>>> for i in range(5):
... print(next(it))
...
2010-01-01 04:00:00
2016-01-01 04:00:00
2021-01-01 04:00:00
2027-01-01 04:00:00
2038-01-01 04:00:00
However, when only concerned with dates within the next 5 years, simply set max_years_between_matches=5 in the above example.
This will result in no matches found, but no additional cycles will be wasted on unwanted matches far in the future.
Find matches within a range using the croniter_range() function. This is much like the builtin range(start,stop,step) function, but for dates. The step argument is a cron expression.
Added in (>=0.3.34)
List the first Saturday of every month in 2019::
>>> from croniter import croniter_range
>>> for dt in croniter_range(datetime(2019, 1, 1), datetime(2019, 12, 31), "0 0 * * sat#1"):
>>> print(dt)
croniter supports Jenkins-style hashed expressions, using the "H" definition keyword and the required hash_id keyword argument. Hashed expressions remain consistent, given the same hash_id, but different hash_ids will evaluate completely different to each other. This allows, for example, for an even distribution of differently-named jobs without needing to manually spread them out.
>>> itr = croniter("H H * * *", hash_id="hello")
>>> itr.get_next(datetime)
datetime.datetime(2021, 4, 10, 11, 10)
>>> itr.get_next(datetime)
datetime.datetime(2021, 4, 11, 11, 10)
>>> itr = croniter("H H * * *", hash_id="hello")
>>> itr.get_next(datetime)
datetime.datetime(2021, 4, 10, 11, 10)
>>> itr = croniter("H H * * *", hash_id="bonjour")
>>> itr.get_next(datetime)
datetime.datetime(2021, 4, 10, 20, 52)
Random "R" definition keywords are supported, and remain consistent only within their croniter() instance.
>>> itr = croniter("R R * * *")
>>> itr.get_next(datetime)
datetime.datetime(2021, 4, 10, 22, 56)
>>> itr.get_next(datetime)
datetime.datetime(2021, 4, 11, 22, 56)
>>> itr = croniter("R R * * *")
>>> itr.get_next(datetime)
datetime.datetime(2021, 4, 11, 4, 19)
Vixie cron-style "@" keyword expressions are supported. What they evaluate to depends on whether you supply hash_id: no hash_id corresponds to Vixie cron definitions (exact times, minute resolution), while with hash_id corresponds to Jenkins definitions (hashed within the period, second resolution).
============ ============ ================
Keyword No hash_id With hash_id
============ ============ ================
@midnight 0 0 * * * H H(0-2) * * * H
@hourly 0 * * * * H * * * * H
@daily 0 0 * * * H H * * * H
@weekly 0 0 * * 0 H H * * H H
@monthly 0 0 1 * * H H H * * H
@yearly 0 0 1 1 * H H H H * H
@annually 0 0 1 1 * H H H H * H
============ ============ ================
<=2021.1.::
git clone https://github.com/kiorky/croniter.git
cd croniter
virtualenv --no-site-packages venv
. venv/bin/activate
pip install --upgrade -r requirements/test.txt
py.test src
We use zest.fullreleaser, a great release infrastructure.
Do and follow these instructions ::
. venv/bin/activate
pip install --upgrade -r requirements/release.txt
./release.sh
Thanks to all who have contributed to this project! If you have contributed and your name is not listed below please let me know.
- mrmachine
- Hinnack
- shazow
- kiorky
- jlsandell
- mag009
- djmitche
- GreatCombinator
- chris-baynes
- ipartola
- yuzawa-san
- lowell80 (Kintyre)
- scop
- zed2015
- Ryan Finnie (rfinnie)
i into global namespace* * R/0 * *
[cuu508]fix bug: bad case:0 6 30 3 *
[zed2015(zhangchi)]
Add support for L in the day_of_week component. This enable expressions like * * * * L4, which means last Thursday of the month. This resolves #159.
[Kintyre]
Create CroniterUnsupportedSyntaxError exception for situations where CRON syntax may be valid but some combinations of features is not supported.
Currently, this is used when the day_of_week component has a combination of literal values and nth/last syntax at the same time.
For example, 0 0 * * 1,L6 or 0 0 * * 15,sat#1 will both raise this exception because of mixing literal days of the week with nth-weekday or last-weekday syntax.
This may impact existing cron expressions in prior releases, because 0 0 * * 15,sat#1 was previously allowed but incorrectly handled.
[Kintyre]
Update croniter_range() to allow an alternate croniter class to be used. Helpful when using a custom class derived from croniter.
[Kintyre]
natsort.
Sorting of cron expression components now handled with sorted() with a custom key function.
[Kintyre]_expand to lowercase each component of the expression.
This is in relation to #157. With this change, croniter accepts and correctly handles * * 10-L * *.
[cuu508]max_years_between_matches to be more shorter and hopefully more relevant.
[Kintyre]max_years_between_matches to support finding the next/previous date beyond the default 1 year window, if so desired. Updated README to include additional notes and example of this usage. Fixes #145.
[Kintyre]croniter_range() function was updated to automatically determines the appropriate max_years_between_matches value, this preventing handling of the CroniterBadDateError exception.
[Kintyre]CroniterBadDateError now only
applies during date finding operations (next/prev), and all parsing errors can now be caught using CroniterBadCronError. The CroniterNotAlphaError exception is now a subclass of CroniterBadCronError. A brief description of each exception class was added as an inline docstring.
[Kintyre]CroniterBadDateError with StopIteration if (and only if) the max_years_between_matches argument is provided. The rationale here is that if the user has specified the max tolerance between matches, then there's no need to further inform them of no additional matches. Just stop the iteration. This also keeps backwards compatibility.
[Kintyre]croniter_range(start, stop, cron)
[Kintyre]#119 <https://github.com/taichino/croniter/issues/119>_.
[kiorky]#114 <https://github.com/taichino/croniter/issues/114>_.
[kiorky]#107 <https://github.com/taichino/croniter/issues/107>_: microsecond threshold
[kiorky]get_next while preserving the fix of get_prev in 7661c2aaa
[Avikam Agur avikam@pagaya-inv.com]get_prev based on datetime.now() is expected to return
current cron iteration and not previous execution.
[Igor Khrol igor.khrol@toptal.com]Real fix for #34 <https://github.com/taichino/croniter/pull/73>_
[kiorky@github]Modernize test infra <https://github.com/taichino/croniter/pull/72>_
[kiorky@github]Release as a universal wheel <https://github.com/kiorky/croniter/pull/16>_
[adamchainz@github]Raise ValueError on negative numbers <https://github.com/taichino/croniter/pull/63>_
[josegonzalez@github]Compare types using "issubclass" instead of exact match <https://github.com/taichino/croniter/pull/70>_
[darkk@github]Implement step cron with a variable base <https://github.com/taichino/croniter/pull/60>_
[josegonzalez@github]start_time parameter is calculated at module init time rather than call time.