Calendar Date Select for Ruby on Rails

CalendarDateSelect is semi-light-weight (about ~20k of javascript/css) and easy to use (but gets even lighter with bundle-fu)! It takes full advantage of the prototype.js library, resulting in less code, but maintaining a great deal of functionality.

Some of it's capabilities:

can pick a date, or a date-time, or a date with an optional time, as a popup selector or an embedded calendar!
speaks several different formats
is easy to localize
is extensible. Calendar Date Select doesn't do everything under the sun (which is a good thing), but you can build on top of it.
Installation / Usage

Install the calendar_date_select gem
sudo gem install calendar_date_select
Add a gem dependency to your rails project (in environment.rb)
config.gem "calendar_date_select"
Then, restart/start your rails project. All necessary files will be copied to your public folder.
Now include this at the top of your layout: (you'll also need to include prototype, if you haven't already!)
<%= calendar_date_select_includes "red" # or "blue", or "silver", or nil for the default! %>
# (if you want more control, you can get a list of stylesheets / javascripts via calendar_date_select_javascripts and calendar_date_select_stylesheets)
See the Demo for various uses of CalendarDateSelect.

Date Calculation in Rails

>> Date.new( 2008, 1, 1 ).to_time.advance( :months => 1 )
=> Fri Feb 01 00:00:00 +0000 2008

>> Date.new( 2008, 2, 1 ).to_time.advance( :months => 1 )
=> Sat Mar 01 00:00:00 +0000 2008

>> Date.new( 2008, 1, 1 ).to_time + 1.month
=> Thu Jan 31 00:00:00 +0000 2008

Extracted from here:

http://roninonrails.blogspot.com/2008/01/beware-of-rails-date-arithmetic.html

Get Month Name in Rails

To get month name as constants, do the following

require 'date'

for i in (1..12)

@month = Date::MONTHNAMES[i]

end

Date Format in strftime

Format	Meaning
%a	The abbreviated weekday name (“Sun'’)
%A	The full weekday name (“Sunday'’)
%b	The abbreviated month name (“Jan'’)
%B	The full month name (“January'’)
%c	The preferred local date and time representation
%d	Day of the month (01..31)
%H	Hour of the day, 24-hour clock (00..23)
%I	Hour of the day, 12-hour clock (01..12)
%j	Day of the year (001..366)
%m	Month of the year (01..12)
%M	Minute of the hour (00..59)
%p	Meridian indicator (“AM'’ or “PM'’)
%S	Second of the minute (00..60)
%U	Week number of the current year, starting with the first Sunday as the first day of the first week (00..53)
%W	Week number of the current year, starting with the first Monday as the first day of the first week (00..53)
%w	Day of the week (Sunday is 0, 0..6)
%x	Preferred representation for the date alone, no time
%X	Preferred representation for the time alone, no date
%y	Year without a century (00..99)
%Y	Year with century
%Z	Time zone name
%%	Literal “%'’ character