How to generate a human readable time range using ruby on rails

There are two methods in DateHelper that might give you what you want:

1. time_ago_in_words

   time_ago_in_words( 1234.seconds.from_now ) #=> "21 minutes"
   
   time_ago_in_words( 12345.seconds.ago )     #=> "about 3 hours"
   

2. distance_of_time_in_words

   distance_of_time_in_words( Time.now, 1234.seconds.from_now ) #=> "21 minutes"
   
   distance_of_time_in_words( Time.now, 12345.seconds.ago )     #=> "about 3 hours"
   

If you need something more "precise" than distance_of_time_in_words, you can write something along these lines:

def humanize(secs)
  [[60, :seconds], [60, :minutes], [24, :hours], [Float::INFINITY, :days]].map{ |count, name|
    if secs > 0
      secs, n = secs.divmod(count)

      "#{n.to_i} #{name}" unless n.to_i==0
    end
  }.compact.reverse.join(' ')
end

p humanize 1234
#=>"20 minutes 34 seconds"
p humanize 12345
#=>"3 hours 25 minutes 45 seconds"
p humanize 123456
#=>"1 days 10 hours 17 minutes 36 seconds"
p humanize(Time.now - Time.local(2010,11,5))
#=>"4 days 18 hours 24 minutes 7 seconds"

Oh, one remark on your code:

(self.created_at..self.updated_at).count

is really bad way to get the difference. Use simply:

self.updated_at - self.created_at