How can you simplify attributes in a model that fold down into the same field in rails?

I have a model called a Message. I have a field called time_received_or_sent stored in the database. A message that is incoming would have a time_recieved and a message that is outgoing would have a time sent. No message would ever have both. Can I combine these in a model so that time_received and time_sent just point to that field when edited? I have four methods in my model that look pretty useless.

  Model Message < ActiveRecord::Base
  ...
    def time_received=(time_received)
      time_received_or_sent = time_received
    end

    def time_received
      return time_received_or_sent
    end

    def time_sent=(time_sent)
      time_received_or_sent = time_sent
    end

    def time_sent
      return time_received_or_开发者_JAVA百科sent
    end
  end

I would prefer something much shorter.

And I'm looking for something other than:

def time_sent; time_received_or_sent; end
def time_received; time_received_or_sent; end
def time_sent=(time_sent); time_received_or_sent=(time_sent); end
def time_received=(time_received); time_received_or_sent=(time_received); end

Although, if this is the best possible, then I'm fine with it.

Model Message < ActiveRecord::Base
...
  alias_attribute :time_sent, :time_received_or_sent
  alias_attribute :time_received: time_received_or_sent
end

You can always use alias_method to collapse these down:

class Message < ActiveRecord::Base
  def time_received=(time_received)
    time_received_or_sent = time_received
  end
  alias_method :time_sent=, :time_received=

  def time_received
    time_received_or_sent
  end
  alias_method :time_sent, :time_received
end 

This is handy for avoiding duplicate implementations of the same method.