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A Python module and program to convert calendars using X-WR-TIMEZONE to standard ones.

Project description

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Some calendar providers introduce the non-standard X-WR-TIMEZONE parameter to ICS calendar files. Strict interpretations according to RFC 5545 ignore the X-WR-TIMEZONE parameter. This causes the times of the events to differ from those which make use of X-WR-TIMEZONE.

This module aims to bridge the gap by converting calendars using X-WR-TIMEZONE to a strict RFC 5545 calendars. So, let’s put our heads together and solve this problem for everyone!

Some features of the module are:

  • Easy install with Python’s pip.

  • Command line conversion of calendars.

  • Piping of calendar files with wget or curl.

Some of the requirements are:

  • Calendars without X-WR-TIMEZONE are kept unchanged.

  • Passing calendars twice to this module does not change them.

Install

Install using pip:

python3 -m pip install x-wr-timezone

Command Line Usage

You can standardize the calendars using your command line interface. The examples assume that in.ics is a calendar which may use X-WR-TIMEZONE, whereas out.ics does not require X-WR-TIMEZONE for proper display.

cat in.is | x-wr-timezone > out.ics
x-wr-timezone in.ics out.ics
curl https://example.org/in.ics | x-wr-timezone > out.ics
wget -O- https://example.org/in.ics | x-wr-timezone > out.ics

You can get usage help on the command line:

x-wr-timezone --help

Python

After you have installed the library, you an import it.

import x_wr_timezone

The function to_standard() converts an icalendar object.

x_wr_timezone.to_standard(an_icalendar)

Here is a full example which does about as much as this module is supposed to do:

import icalendar # installed with x_wr_timezone
import x_wr_timezone

with open("in.ics", 'rb') as file:
    calendar = icalendar.from_ical(file.read())
new_calendar = x_wr_timezone.to_standard(calendar)
# you could use the new_calendar variable now
with open('out.ics', 'wb') as file:
    file.write(new_calendar.to_ical())

to_standard(calendar, timezone=None) has these parameters:

  • calendar is the icalendar.Calendar object.

  • timezone is an optional time zone. By default, the time zone in

    calendar['X-WR-TIMEZONE'] is used to check if the calendar needs changing. When timezone is not None however, calendar['X-WR-TIMEZONE'] will not be tested and it is assumed that the calendar should be changed as if calendar['X-WR-TIMEZONE'] had the value of timezone. This does not add or change the value of calendar['X-WR-TIMEZONE']. You would need to do that yourself. timezone can be a string like "UTC" or "Europe/Berlin" or a pytz.timezone or something that datetime accepts as a time zone..

  • Return value: The calendar argument is not modified at all. The calendar

    returned has the attributes and subcomponents of the calendar only changed and copied where needed to return the proper value. As such, the returned calendar might be identical to the one passed to the function as the calendar argument. Keep that in mind if you modify the return value.

Development

  1. Clone the repository or its fork and cd x-wr-timezone.

  2. Optional: Install virtualenv and Python3 and create a virtual environment:
    pip install virtualenv
    virtualenv -p python3 ENV
    source ENV/bin/activate # you need to do this for each shell
  3. Install the packages and this module so it can be edited:
    pip install -r test-requirements.txt -e .
  4. Run the tests:
    pytest

New Releases

To release new versions,

  1. edit the Changelog Section

  2. edit setup.py, the __version__ variable

  3. create a commit and push it

  4. Wait for CI tests to finish the build.

  5. run
    python3 setup.py tag_and_deploy
  6. notify the issues about their release

Testing

This project’s development is driven by tests. Tests assure a consistent interface and less knowledge lost over time. If you like to change the code, tests help that nothing breaks in the future. They are required in that sense. Example code and ics files can be transferred into tests and speed up fixing bugs.

You can view the tests in the test folder. If you have a calendar ICS file for which this library does not generate the desired output, you can add it to the test/calendars folder and write tests for what you expect. If you like, open an issue first, e.g. to discuss the changes and how to go about it.

Changelog

  • v0.0.5
    • Revisit README and CLI and fix spelling mistakes.

    • Modified behavior to treat events without time zone found in a calendar using the X-WR-TIMEZONE property, see Pull Request 7

  • v0.0.4
    • Test automatic deployment with Gitlab CI.

  • v0.0.3
    • Use tzname() function of datetime to test for UTC. This helps support zoneinfo time zones.

    • Split up visitor class and rename it to walker.

  • v0.0.2
    • Implement the timezone argument.

    • Do not modify the value of the calendar argument and only copy it where needed.

  • v0.0.1
    • Initial release supports DTSTART, DTEND, EXDATE, RDATE, RECURRENCE-ID attributes of events.

    • Command line interface as x-wr-timezone.

License

This software is licensed under LGPLv3, see the LICENSE file.

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