agenda-libre-ruby/app/views/events/show.ics.haml

:ruby
  # Create a calendar with an event (standard method)
  cal = Icalendar::Calendar.new
  tzid = @event.region.tzid
  cal.event do |e|
    e.dtstamp     = Icalendar::Values::DateTime.new @event.decision_time, tzid: tzid
    e.uid         = "#{event.id}@#{request.domain}"
    e.dtstart     = Icalendar::Values::DateTime.new @event.start_time, tzid: tzid
    e.dtend       = Icalendar::Values::DateTime.new @event.end_time, tzid: tzid
    e.summary     = @event.title
    e.description = to_markdown @event.description.tr '\'', '’'
    e.location    = @event.full_address
    e.organizer   = "mailto:#{@event.contact}"
    e.x_alt_desc  = Icalendar::Values::Text.new @event.description, FMTTYPE: 'text/html'
  end

  cal.publish

= cal.to_ical