user_activity.rb

def last_activity_description(date, user_id)
  user_activity = UserActivity.find(:first, :conditions => ["Date(updated_at) <= ? and user_id = ?", dat
e, user_id], :order => 'updated_at DESC')
  user_activity.activity.description
end

# better
def last_activity(date, user_id)
  UserActivity.find(:first, :conditions => ["Date(updated_at) <= ? and user_id = ?", dat
e, user_id], :order => 'updated_at DESC').activity
end

last_activity(date, user_id).description