Ruby Date 1 month ago to String

Try this:

require 'date'

d = Date.today.prev_month # or Date.today.next_month, depending what you want
 => #<Date: 2014-12-27 ((2457019j,0s,0n),+0s,2299161j)> 
d.strftime("%FT%T")
 => "2014-12-27T00:00:00" 

Try this:

2.0.0-p247 :004 > require 'date'
 => false 
2.0.0-p247 :005 > Date.today.prev_month
 => #<Date: 2014-10-27 ((2456958j,0s,0n),+0s,2299161j)> 
2.0.0-p247 :006 > Date.today.prev_month.to_s
 => "2014-10-27" 
2.0.0-p247 :008 > Date.today.prev_month.strftime("%F%T")
 => "2014-10-2700:00:00" 
2.0.0-p247 :009 >