Do not output DTSTART in toString()

[espen]

DTSTART and DTEND is not part of iCalendar RRULE and should not be included when doing .toString().

Perhaps generate something like "DTSTART=x;DTEND=x;RRULE=x" which would be valid iCalendar syntax.

[GeoffreyEmery]

also plus 1 this

[fredpalmer]

Agreed - this is causing some grief when interoperating with other implementations (e.g. Python dateutil)

[tilthouse]

👍 for this issue

AFAIK, DTSTART is always supposed to be a different line, not just delimited by ;, so like the example referenced in #84 (newlines are significant):

DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000Z;WKST=SU;BYDAY=MO,WE,FR

I do not think (but await correction if wrong) that concatenating these lines with a ; is valid RFC 5545.

[tiltec]

@jkbrzt do you accept Pull Requests for this?

Since this would be a breaking change, I could imagine implementing it in a separate function, e.g. icalString() and give an option to the parser as well.

[jorroll]

For anyone else running across this issue, I created a helper function which seems to work for my needs (note: it's written in typescript)

export function rrulesetToIcalString(schedule: RRuleSet, startDate: Moment): string {
  // matches `;DTSTART=20180125T080000Z` until `;` or end
  const icalStrings = schedule.valueOf().map(ruleString => ruleString.replace(/;DTSTART=.*?(?=(?:;)|$)/, ''));

  icalStrings.unshift(`DTSTART;TZID=UTC:${startDate.utc().format('YYYYMMDDTHHmmss')}`);

  return icalStrings.join('\n');
}

You give it a RRuleSet and a startDate (I set it up for use with Moment dates, but you get the idea) and it goes through and removes any ;DTSTART=...; sections in the RRuleSet. It then adds one, properly formatted DTSTART section at the beginning of the RuleSet, and then it joins all the sections together.

Note: I think there's only suppose to be one DTSTART value present. Maybe there are iCalendar flavors where this isn't true, however (outside my use case).

[phillbaker]

To get a compliant rrule string (without the DTSTART), one option is to use RRule.optionsToString directly:

var rule = new RRule({
   freq: RRule.WEEKLY,
   interval: 5,
   byweekday: [RRule.MO, RRule.FR],
   dtstart: new Date(2012, 1, 1, 10, 30),
   until: new Date(2012, 12, 31)
});
var copy = Object.assign({}, rule.origOptions);
delete copy.dtstart
RRule.optionsToString(copy)

[indexofmetals]

Any update on this? Not too difficult to get a compliant rrule string, thanks to @phillbaker's advice, but would be nice to be able to plug and play with Python's dateutil.

[davidgoli]

Agreed, there are some differences in syntax with the RFC and with Python. Would be very open to a pull request addressing this!

[davidgoli]

Now that TZID has been implemented (#261), the library can no longer parse strings that it outputs. I think a backwards-compatible solution can be reached by continuing to parse pre-2.4.0 output strings, but outputting RFC-compliant strings.

[davidgoli]

^ my last statement here ("the library can no longer parse strings that it outputs") is now incorrect, this was just fixed by #267. Still, it would be ideal to conform to the RFC!

[davidgoli]

Fixed by #269