recurring events solutions

[fyliu]

Starting a discussion about solutions for recurring events.

It turns out there's new one that showed up recently.

• django-recurrence
• django-recurring

[fyliu]

I added both to the current main code and we can see inside the Event model that:

• recurrences is a RecurrenceField
• calendar is a ForeignKey to CalendarEntry in the recurring namespace

[fyliu]

In terms of interface

The RecurrenceField is more elegant in that it exposes a set of functions that it provides.

• drawback: we're trusting the underlying code to work correctly and provide what we need.

The CalendarEntry is a ForeignKey, and allows us to work with the underlying tables directly.

• drawback: we need to write code to work with the tables internal to recurring ourselves. We need to know what's inside.

[fyliu]

I tried to create the general onboarding schedule, which is every 2 weeks, alternating between Monday and Tuesday.

Here's RecurrenceField with the UI showing in the Event object itself:

Here's recurring, which is in its own object linked from the Event object.

[fyliu]

Comparison:

• While django-recurrence RecurrenceField supports multiple rrules, the UI widget doesn't allow setting separate start and end times for each rrule. So it's impossible to create the desired schedule with it where, for example, the Monday schedule is for this week and the Tuesday schedule is for 2 weeks from now.
• With django-recurring, it's possible to create the desired schedule.
  • negative: The CalendarEntry model includes name and description fields, which duplicates the data from our Event model.
  • positive: This package supposedly has the timezone conversion figured out.
  • negative: This package implements a newer RFC than the other one, where exrule is deprecated and not implemented. That means no excluding the first week of the month for CoP-leads meetings.

[fyliu]

I learned that Hackforla doesn't really make use of an alternating Monday Tuesday schedule and that Bonnie chooses the dates to manually work around holidays and other special dates. So there's no need for the alternating Mon/Tue requirement.

[fyliu]

event recurrence requirements from a past meeting

• ok to get list of only non-deleted event instances for mvp
  • may need to get all instances with deleted flag in future milestone
• need the ability to checkin users to event instances
  • mainly the ability to identify instances uniquely even if the instance object is not created
  • maybe something like event.id and "event".start_time and "event".end_time
• ability to modify events?
  • [future instances] gcalendar will set the end date on the existing event and create a new copied event for the modified one. Sort of a copy-on-write solution.
  • [all instances] if we allow modifying the actual original event as in "modify all instances", what would happen to all the checkins where the start_time is now modified? We can't really have that. The new event may also need to point to the old event for lookup
• recurrence capabilities
  • single occurrence
  • weekly (Team)
  • monthly (CoP-Leads)
  • biweekly alternating Mon-Tues (onboarding)
  • exclusion rrule (Team - CoP-Leads) - exrrule is deprecated in RFC33xx but we do need it

[fyliu]

so, essentially, a single rrule and a single exrrule will do it.

This means recurring won't cover our needs, since it doesn't support exrrule.
recurrence won't work either, since it provides only the RecurrenceField, which has a very limited set of possible operations.

Next, I will look at the internal components of both packages to see if we can at least use their rrule implementation.

[fyliu]

It looks like we can use recurrence for some of its implementation.

I looked at the recurrence tests and saw that it's possible to use the Rule and Recurrence classes directly. Rule is essentially rrule and Recurrence is a complete recurrence schedule including "DTSTART, DTEND, RRULE, EXRULE, RDATE, and EXDATE", according to the documentation.
These are the ones useful to us:

• DTSTART, DTEND for the date range limits
• RRULE, EXRULE for recurrence rule and exclude recurrence rule
• RDATE, EXDATE for individual include and exclude datetimes

Links:

• https://github.com/jazzband/django-recurrence/blob/master/recurrence/base.py
• https://github.com/jazzband/django-recurrence/blob/master/tests/test_fields.py

[fyliu]

The next step is to see if we can add some code to implement the peopledepot meeting schedule and store that in the Event model somehow, where we can recall the schedule in django and do something useful with it, like these:

• "is this event happening today? an instance of it"
• "get a list of instances over a date range"
• "add an exrule"
• "add rdates"
• "add exdates"
• ...