Creating an event with recurring dates

event.rb

class Event < ActiveRecord::Base
  attr_reader :start_date, :end_date, :days
  
  has_many :performances
  
  def build_performances
    (start_date..end_date).each do |date|
      next unless days.include? date.wday
      self.performances << Performance.new(date: date)
    end
  end
  
  def start_date=(date)
    @start_date = Date.parse(date)
  end

  def end_date=(date)
    @end_date = Date.parse(date)
  end

  def days=(days)
    @days = days.map(&:to_i)
  end
end

events_controller.rb

class EventsController < ApplicationController
  def new
    @event = Event.new
  end

  def create
    @event = Event.new(event_params)
    @event.build_performances
    @event.performances.each do |p|
      logger.info p.date
    end

    redirect_to :back
  end

private

  def event_params
    params.require(:event).permit(
      :name,
      :start_date,
      :end_date,
      days: []
    )
  end
end

new.html.erb

<%= form_for @event do |f| %>
  <%= f.label :name %>
  <%= f.text_field :name %>

  <% Date::DAYNAMES.each_with_index do |day, i| %>
    <%= check_box_tag "event[days][]", i, false, id: day.downcase %>
    <%= label_tag day.downcase, day %><br>
  <% end %>

  <%= f.label :start_date, 'Start Date' %>
  <%= f.date_field :start_date %>

  <%= f.label :end_date, 'End Date' %>
  <%= f.date_field :end_date %>

  <%= f.submit %>
<% end %>

play.rb

require 'date'

class Recurrence
  attr_reader :days, :start_date, :end_date

  def self.every(*days, options)
    new(days, options).dates
  end

  def initialize(days, options)
    self.days = days
    self.start_date = options[:from]
    self.end_date = options[:to]
  end

  def days=(days)
    @days = days.uniq.map do |day|
      Date::DAYNAMES.index day.to_s.capitalize
    end
  end

  def start_date=(date)
    @start_date = Date.parse(date)
  end

  def end_date=(date)
    @end_date = Date.parse(date)
  end

  def dates
    (start_date..end_date).select do |date|
      days.include? date.wday
    end
  end
end

Recurrence.every :monday, :tuesday, from: '2013-05-18', to: '2013-06-02'