rrule

rrule is a minimalist library for expanding RRULEs, with a goal of being fully compliant with iCalendar spec.

To install this gem, add it to your Gemfile:

gem 'rrule'

Create an rrule with an RRULE string:

rrule = RRule::Rule.new('FREQ=DAILY;COUNT=3')
rrule = RRule.parse('FREQ=DAILY;COUNT=3') # alternate syntax

Either generate all instances of a recurrence, or generate instances in a range:

rrule.all
=> [2016-06-23 16:45:32 -0700, 2016-06-24 16:45:32 -0700, 2016-06-25 16:45:32 -0700]
rrule.between(Time.new(2016, 6, 23), Time.new(2016, 6, 24))
=> [2016-06-23 16:45:32 -0700]

You can generate all instances starting from a specified date with the #from method:

rrule = RRule::Rule.new('FREQ=DAILY;COUNT=3', dtstart: Time.new(2016, 1, 1))
rrule.all
=> [2016-01-01 16:45:32 -0700, 2016-01-02 16:45:32 -0700, 2016-01-03 16:45:32 -0700]
rrule.from(Time.new(2016, 1, 2))
=> [2016-01-02 16:45:32 -0700, 2016-01-03 16:45:32 -0700]

You can limit the number of instances that are returned with the limit option:

rrule = RRule::Rule.new('FREQ=DAILY;COUNT=3')
rrule.all(limit: 2)
=> [2016-06-23 16:45:32 -0700, 2016-06-24 16:45:32 -0700]

By default the DTSTART of the recurrence is the current time, but this can be overriden with the dtstart option:

rrule = RRule::Rule.new('FREQ=DAILY;COUNT=3', dtstart: Time.new(2016, 7, 1))
rrule.all
=> [2016-07-01 00:00:00 -0700, 2016-07-02 00:00:00 -0700, 2016-07-03 00:00:00 -0700]

Unless your rrule should be evaluated in UTC time, you should also pass an explicit timezone in the tzid option to ensure that daylight saving time boundaries are respected, etc.:

rrule = RRule::Rule.new('FREQ=DAILY;COUNT=3', dtstart: Time.new(2016, 7, 1), tzid: 'America/Los_Angeles')

To define exception dates, pass the exdate option:

rrule = RRule::Rule.new('FREQ=DAILY;COUNT=3', dtstart: Time.new(2016, 7, 1), exdate: [DateTime.parse('2016-07-02 00:00:00 -0700'])
rrule.all
=> [2016-07-01 00:00:00 -0700, 2016-07-03 00:00:00 -0700]

Copyright 2018 Square Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.