Rails - Sep 2005 - ActiveRecord default behavior with DateTime

Hye,

I try to store DateTime as integer (seconds) in my database (MySQL).
I''d like to convert seconds to DateTime in the ActiveRecord object 
 to handle it easily in my views.
I try to play with callbacks or with method dedicated to my attributes for eg.

def fetched
  upd = nil
  v =read_attribute(:fetched)
  if (v)
    upd = DateTime.at(v)
  else
    upd = DateTime.now
  end
end

def fetched=(y,m,d,h,mn)
  v = DateTime.new(y,m,d,h,mn)
  write_attribute(:fetched, v.to_i)
end

but I feel it may not be the right way.

How do you think I should handle that ?