## calendars_controller.rb

class CalendarsController < ApplicationController

  # GET /ui_prototype
  def index
    @dates = dates_of_month today.year, today.month
  end

protected

  # Return an array of days from sunday to saturday of the given month
  # and year, includes previous and next months / years if needed
  def dates_of_month(year, month)
    first = Date.new(year, month, 1)
    last = Date.new(year, month + 1, 1) - 1
    start_date = first - first.wday
    end_date = last + (6 - last.wday)

    dates = Array.new
    start_date.upto(end_date) do |d|
      dates.push(d)
    end
    return dates
  end

end

## calendars_helper.rb

module CalendarsHelper

  def date_dom_id(date)
    return "#{date.year}_#{date.month}_#{date.day}"
  end

  def date_dom_class(date, week)
    return "calendar-datecell-week-5-day-6" if week == 5 and date.wday == 6
    return "calendar-datecell-week-5"       if week == 5
    return "calendar-datecell-day-6"        if date.wday == 6
    return "calendar-datecell"
  end

end

## index.rhtml

<div id="calendar_container">
<%
    week = 1
    @dates.each do |d|
%>
  <div id="<%= date_dom_id(d) %>" class="<%= date_dom_class(d, week) %>">
    <div id="<%= "day_#{date_dom_id(d)}" %>" class="calendar-day"><%= d.day -%></div>
  </div>
<%
    end
%>
</div>

## error message

 NoMethodError in Calendars#index

Showing app/views/calendars/index.rhtml where line #4 raised:

You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each